I wanted to make a quick guide on how you can really make a difference in WvWvW with various sized groups, what you should be targetting, and how you go about it. I'm going to break this up into various group sizes and explain what you need to do to maintain control of a map.
- Do not build glass cannon. It's extremely ineffective in all modes of play of Guild Wars 2, but especially WvWvW. You need to have a good amount of vitality and possibly a decent number of toughness too. Plate classes do not need toughness as they already have a high "Defense" value from gear already (your actual mitigation is based on toughness + defense which mitigates all damage except condition DOT damage). A build with vitality and toughness will absolutely devestate a glass cannon build. Aside from this, a lot of times you'll be facing seige on the other side or manning a seige weapon where you are essentially unprotected. You'll also likely have to tank damage from Guards at some point in time. You need to be able to take hits.
- You do not need two range weapons. You should be using a balance of ranged and melee. You don't need a long range weapon either, as that is what seige is for. Melee weapons are MUCH stronger than range (with maybe a few exceptions like Elementalist) and they are the perfect weapons for infantry skirmishes.
- Don't clump together in big groups when dealing with seige weapons. It's much more effective to spread out.
- Keep moving when you are attacking poorly defended seige. Use buildings and line of sight against seige to get closer to seige. Simply moving prevents Ballistas from hitting you at long range for example. Keep an eye out for red circles on the ground and get out of them. Some slower seige like Mortars can be easily dodged by watching the Mortar shots.
- Avoid taking supply from towers unless that tower is being seiged. Supply on a tower is absolutely critical to defense. Take the extra time to go to a supply camp to get your supply if the danger isn't immediate.
- Have someone watching the map at all times. As soon as you see an attack (indicated by dual swords) respond to it. It may just be a player running by and attacking the NPCs, but it could be a group of players trying to take your camps undefended. If possible place scouts across the map.
- Stay active. If you aren't doing anything scout, or check the dynamic events, or watch your supply caravans.
- The closer you are to enemy spawn points the more likely you are to deal with large (and constant) zergs from those enemies. Taking a tower next to the enemy spawn point for example will simply mean you could be in for a long drawn out seige as wiping the enemy out will not result in a huge setback for the enemy.
- Sometimes simply killing a tower or keeps supply is a victory. Attack one point with a small force and have them spend all their supply on that point. They'll probably wind up winning or pushing you out, but they'll likely now be completely out of supply. Attack the other side and they'll probably have little means of defending it.
- It's important to keep a steady stream of supply going when doing seiges. Have someone (or multiple people) doing constant runs to a nearby supply camp to feed supply. Take turns swapping out and doing these runs so you always have everyone with maximum supply. Spending influence on increasing your maximum supply you can carry helps immensely with this too.
- Skirmish if you can afford it. Have players posted outside points and bait other players and groups to your seige weapons for easy and quick kills. Your most mobile players are your best bet for skirmishers.
Seige Weapons and Upgrades:
Notes on Upgrades - Everytime you upgrade a camp, tower, or keep the total supply that point can hold will increase. Holding the point till any upgrade completes will also reward EXP, Karma, and Gold to anyone who held the point while the upgrade was completing, making it a great way to get EXP and Karma. Your group should take turns spending silver on upgrading each point as much as possible.
Burning Oil - This comes from the first set of weapon upgrades on a tower or keep. It will add a large burning oil pot to your front door. The damage is massive (possibly higher than any other seige weapon over time) and as long as you have one the enemy will think twice about using the front door on a seige which has roughly half the HP of any wall. Burning Oil can be taken down with a lot of ranged focus, but as long as you have other seige this can be nearly impossible. If you encounter Burning Oil on a door you should focus your efforts on a poorly defended wall somewhere else on the Keep instead.
Cannon - This is the next set of weapon upgrades on a tower or keep. It adds a long range anti-infantry and seige artillery weapon. It does decent damage, but a single cannon usually isn't enough to kill off larger groups of people especially when no supported by other means as it is fairly easy to dodge most of the attacks. It doesn't have a lot of health and the cannons are placed in vulnerable positions, but the addition of cannons can make the start of an assault much more difficult on your opponent as they are cheap seige weapons.
Mortar - Mortars are basically longer ranged versions of the cannon. They are placed in significantly safer positions than the cannon making them difficult to reach and stop. Having this upgrade helps significantly with the control of the Keep. The shots from very long range are even easier to dodge than a cannons, but against larger zergs they can be a nightmare to deal with.
More Guards - This is a great upgrade to have in supply camps especially. It generally gives you enough time to deal with larger groups of players attacking a supply camp you may not be in a position to readily defend. It also lets you pelt the enemy with seige weapons while they are dealing with the guards in the outer areas of a camp. If a group attempts to rush you without dealing with the guards first it will generally result in a failure.
Upgraded Guards - This adds a Zealot to your defenses. Zealots are Guards on steroids, providing decent CC, but more importantly an AoE whirlwind attack that can bring down squishier classes in seconds. Attempting to take down a camp with a Zealot still active will generally result in a wipe for the opposing party.
Dynamic Event Guards - The reward for completing dynamic events to help NPC factions in the area is that they send powerful units to your supply camp. These are equivalent to having a Zealot on your defenses with generally hard to deal with NPCs (such as a Wizard pelting people with 6k damage lightning bolts). It's generally recommended that whenever possible to complete these dynamic events as they don't take very long and the reward is outstanding.
Arrow Carts - These are short range AoE damage anti-infantry weapons. Try to place them as high on places as possible as this will increase their range. Use the crippling shot to make it easier for other more powerful seige weapons to kill players such as Ballistas. The biggest advantage of these is that they can be placed out of sights (essentially untargettable) on Keeps and Towers making them one of the best options for short range defense on those. They can also shoot around buildings to extent, making them decent support for Ballistas on supply camps. Their damage isn't fantastic, and a tanky person can easily just sit inside one and revive downed players and such, so don't rely on a single arrow cart completely for your defense. They are the cheapest seige (at 4s) and cost only 30 supply.
Ballistas - These are the ultimate anti-infantry weapons and make great anti-seige too. Each attack on the Ballista does roughly 6-7k damage on infantry units. The first attack is a standard short cooldown anti-infantry bolt. The second attack shoots an exploding bolt that splashing for full damage around anyone or anything it hits and also puts a bleed on the target. This bolt can hit a little past the Ballistas max range as it does damage at it's max range + splash range, so it can be used as anti-seige against a seige placed just slightly out of the Ballistas range. The third attack fires a bolt that does double damage versus seige weapons and makes this a very hard weapon to place seige against. Keep in mind Ballistas attacks can be dodged easily by simply moving at long range. At 6s and a mere 20 supply Ballistas are a perfect weapon to quickly destroy large groups of enemy zergs and make it difficult for them to place seige down. These are highly recommended for both assaulting towers and keeps, supporting other seige, and defending supply camps. For placement Ballistas should be placed as out in the open as possible. Like Arrow Carts placing them high up will give them a ranged advantage. Never place them next to buildings and such, as this provides enemies an easy way to approach them. Never place other Ballistas near other as this makes them prone to AoE.
Catapults - A fantastic seige assault weapon. You charge the catapult up by holding down the attack key and releasing it once you have the optimal level of power. The longer you hold the charge the further the catapult will fire. Against well defended towers and keeps you should place the catapult as far away as possible. If you simply want to take down the wall faster, place the catapult closer. At 50 supply and 8s these can be quite costly, but their high range makes them hard to deal and a fantastic way to take down walls from a safe distance.
Trebutchets - These are essentially more powerful versions of the catapult. Even longer range than a catapult and having a very decent anti-infantry attack to boot, these are pretty much the ultimate weapon when it comes to taking down a tower or Keep. Place them very far back and watch them rain fiery death (or poisonous cows) on your poor opponents. At 16s and 100 supply these are extremely costs though even a small group can use them with a steady supply run.
Seige Golems - I feel these are more aethestic than serve a partical purpose. They give you a decent amount of HP (~150k I think) and do massive damage to infantry and buildings alike, but they are extremely slow and easy to deal with out in the open. At their gold and supply cost they really aren't worth the cost and you are better off using Ballistas and Arrow Carts for Infantry and Catapults and Trebutchets for seige.
Dealing with any guard - If you have the option have pets tank the guards. Pets can tank any guard type very well
Supervisor - These are found at supply camps. They do a lot of melee damage, but are easily kited. They have a lot of HP and defense and heal for a lot (try to poison them before they heal to reduce this). Generally you can just deal with these last as they aren't much of a threat.
Guards - These are tanky and provide a bit of CC. It's not a bad idea to prioritize them quickly and they are easy to pull back to a safer position.
Archers - They deal a decent amount of ranged damage. They drop pretty easily, but generally you are in a better position to deal with melee units first. Pull the melee units away and deal with them then deal with archers. Do not drop down seige blueprints with archers near as they tend to pelt the seige blueprints before you can put supply on it, wasting the blueprint entirely.
Scouts - These are extremely annoying. Their damage isn't particularly high, but they'll blind whoever is doing damage to them to the point where that person will barely be doing any damage and faster than you can remove it. Whenever possible have a pet deal with this, as they'll take the blind without much of a noticable effect.
Zealots - These are extremely tanky, heal for a lot, have massive HP, and deal massive AoE damage. Try to pull these alone and deal with them as soon as possible. Do not attempt to engage a camp, tower, or keep till these are dealt with.
Tower and Keep Lords - Tower Lords are very managable with 3 players, but they have a lot of HP so it's recommended to build a Ballista to DPS them down. They have a PB AoE, but anyone can tank them easily with the right build especially Ranger pets. Hold them in place and let the Ballista and ranged DPS do their jobs. Be careful not to reset them as they have a short leash. Keep Lords on the other hand can be much harder to deal with. It's recommended you get a few ballistas and a few people swapping out the tanking role to deal with one. The AoE is also much larger too, so players should be aware of it.
Other NPCs - These are generally from winning dynamic events nearby. They are quite powerful and should be regarded as a threat equal to the Zealots. Take them out quickly.
Group Sizes and Tactics:
2 players - Buy lots of Ballistas and take over a nearby supply camp with a single choke point. You may need to use a Ballista to take over the supply camp if you do not have enough damage. Build 2 Ballistas on the supply camp (seperate them enough distance from each other) and wait for people to pour in from the choke point. Rain AoE death and rake in the EXP, badges, and loot. You can generally do this for hours before they get organized enough to rush in and take down the Ballistas.
3 to 5 players - The goal is to control a large areas of the map with just 3 to 5 players here. Have each player buy several Ballistas, a few Arrow Carts, a few Flame Rams, and a Catapult each. Take an area with 3 supply camps and 2 towers. Start by taking both of the supply camps (using similar tactics to the 2 player tactics) surronding the first tower and wait to at least get the majority of the guard upgrades here. Once the supply camps are well secured work on taking the tower. If the tower has defenses up you'll probably need to whittle down and make them waste supply on one side and then attack the other side while it has no supply. You'll need to make several supply runs doing this (especially if you only have 3 people) and make sure when you take the wall or keep door down you have everyone with full supply. Build a Ballista to take the Tower Lord down faster. Once you have this tower secured spend time upgrading and defending it. Watch the supply camps and make sure none get stolen. Finally move on to taking the final supply camp and tower and simply hold all 5 points as long as you can. You'd be suprised how fast all the EXP and karma adds up between all the seige weapon kills and bonuses from upgrading and defense.
6 players to 10 players - Add another supply camp and a keep to your overall goals. This should be easy enough. Pretty much go on the same tactics here, except you have much more flexiblity on what you can buy and who spends what. You'll be getting a decent amount of income as long as you split duties on upgrading and who spends what on seige. Keeps themselves will require a lot of supply to take down I recommend a Ballista and 2 Flame Rams per wall undefended and against defended ones you'll want more Ballistas and Catapults instead of Rams (or better yet Trebutchets). When you fight the Keep Lord you should build a lot more Ballistas to keep steady damage on him (and keep other defending players from coming to assist) and you'll need people taking turns taking him to keep him away from your seige.
11+ players - Focus on controlling and upgrading the entire map. If you get everything upgraded there is pretty much nothing that can stop you beyond another organized group. If you have more than one raiding party this size you may want to consider controlling the Eternal Battlegrounds even or trying to control 2 maps at once (a surefire way to singlehandedly win WvWvW as a single guild). Don't be afraid to split up your group as much as possible here, there generally isn't much of a need for a group beyond 10 players in one spot in WvWvW once you are on the defensive.