Warp is one of the most useful power in Mass Effect 3 Multiplayer and, indeed, the Singleplayer. It can be used on shields and health but is most effective on armor and barriers, especially if you choose certain buffs in the ranking of Warp.
The first three buffs to warp are straight forward because you don’t have a choice. They offer minor improvements to the overall power.
Your first choice is on rank 4. You can either choose a 30% damage buff or a 50% increase in force, damage and impact radius of combo detonations (which are biotic detonations). If you don’t know what these are, I have written a guide that explains what they are and how to use biotic explosions here. You should focus on combo detonations at all times when they are offered to you because biotic explosions much more powerful and versatile than any one power on its own. So whenever you have a choice between anything and combo detonations/biotic explosions always choose them.
Next you can choose between a 40% damage and 60% duration buff or a 15% weapon and power damage increase. Here it really just depends on what you want to focus on. If you want to kill basic enemies as fast as possible you would go for the damage and duration buff. But if you want to make Warp more useful in all situations you go for the latter. This is especially useful because from what I have noticed the effect stacks, so if you put it on en enemy and within the 10 seconds you put it on the same enemy again you get a 21% instead of a 10% buff.
Last you can choose between Warp being more effective on barriers and armor or reducing the recharge time. The recharge time numbers are actually somewhat misleading. If you reduce 2.46 seconds by 35% you end up with 1.60 seconds. However, the buff only reduces it to about 2.2 seconds. The reason for that is that the individual buff isn’t 35% but the buff on the original power is 35%. On rank 2 you get a 25% buff to recharge time already so this tier only offers a 10% reduction. Anyway, what I am saying is that the recharge time buff isn’t that good because you won’t notice the difference of 200 ms. The other buff is much more useful and you will notice the difference in combat. It is also very easy to calculate which is more useful against targets that have barriers and armor. The recharge buff provides an additional 10% of damage to everything and the other provides a 50% increase only to barriers and a 75% increase to armor.
Warp Combat Strategies
The combination of spamming warp and a vanguard charging into a group of enemies where one enemy is warped is one of the most effective tactic in the Mass Effect 3 multiplayer. It makes the vanguard about 300% more effective because on top of the area damage of biotic charge and nova warp is damaging one enemy and the biotic explosion is doing very powerful area damage on top of all that. If you are playing with a vanguard be sure to follow the vanguard around and warp any group of enemies the vanguard is about to charge. I have written a guide to using the vanguard effectively here.
Otherwise you want to focus on as many biotic explosions as possible. If you are playing as an adept your other biotic abilities will be able to set off biotic explosions once you have put warp on an enemy. Only the Drell Adept doesn’t have warp. The Human Sentinels and Turian Sentinel also have warp, but only the humans can set off biotic explosions because overload does not set off combo detonations.
Warp will work on any enemy. It works on shields and health but is most effective on armor and barriers. But regardless of what you put it on it will always set off biotic explosions in combination with other biotic powers.