The reptilian drell have dense muscle tissue that grants them surprising, wiry strength. With unique hyoid bones in their throats, drell can vocalize high-pitched sounds outside of human hearing range. The bones have the added benefit of making drell extremely difficult to strangle.
Though drell may lack the rugged durability of other races, they are lightning fast and deadly accurate. Drell are to be feared on the battlefield.
Biotic Strike - The Drell Vanguard strikes at enemies with a biotically-charged fist.
Acrobatics - The Drell Vanguard rolls to quickly evade incoming attacks and flips over obstacles.
Drell Vanguards have very low barriers, resulting in an endurance lower than nearly every other class with only 900 health and 450 barriers at best. However they are much faster than other classes.
Cluster Grenades are lethal against groups, especially in combination with Biotic Explosions.
Pull will leave your opponents helpless and vulnerable to biotic detonations--the Drell Vanguard can detonate them with either Charge or Cluster Grenades.
If going for just Biotic Charge and Cluster Grenades, one can afford a moderate loadout. If Pull will be used, consider a light loadout so one can constantly yank unprotected, unarmored enemies off the ground. A possible loadout would be a shotgun with pistol in order to balance out firepower and charge cooldown. Alternatively, a Talon can deliver serious damage whilst being very light; at close quarters, it is preferable to the Paladin or Carnifex.
Since you are physically weak, it is highly recommended to stick to cover whenever possible. Biotic Charge should be used only when necessary, rather than as a tool of aggression. However, with intelligent selection of the final evolution, it can be used constantly to replenish barriers when combined with a light loadout.
Alternatively if one goes for the 150% recharge speed evolution at rank 6 of Pull, you could even afford to bring a heavy loadout, albeit at the cost of a long cooldown for Biotic charge. Or you could forego Biotic Charge altogether, as said power only restores 125-450 barriers, which won't last long against enemies on Gold or Platinum. This would make you much more flexible in how you can deal with enemies, rather than just through the use of powers and aggressive CQB tactics.
Since speed is a drell's main strength, there is a much smaller chance of being instantly killed by the Phantom's Impale move, but caution should be exercised nonetheless.
Pull will prove invaluable against Guardians, since they solely rely on their shields for protection. Yank away their shields, and they become nothing more than a basic Assault Trooper. Timed correctly, it can also be used against Phantoms as they cloak, as it'll force the Phantoms to land which can give you enough time to take them down. Dragoons are the only humanoid target in this faction that is immune to your pulling due to its armor and Atlases cannot be pulled for obvious reasons.
Your Cluster Grenades will work wonders here, since all enemies except Marauders and Banshees have only armor or health. Since most enemies are either big, or slow moving and weak, you can easily, with precision throwing, take out huge groups of enemies in a short space of time, even on Gold. You could even take a heavier-than-normal loadout, just to make sure you have some anti-armor weapons to aid you against the Reapers.
It is easier for you to get away from Banshees, but you are no less vulnerable than other races. Avoid close quarters with a Banshee, you will likely end up lifeless and spectating the rest of the round.
Cluster Grenades are a must here, since all geth (with the exception of the basic trooper), have at least some kind of shielding. Hit your enemies hard, as your enemies will certainly be hitting you hard, especially the Geth Hunters, Primes, and Rocket Troopers with their ability to stun and destroy your shields and health in just three shots.
Caution is highly recommended: stick by your team and stay behind cover, as you will otherwise find yourself going down very often.
Charge weaker enemies if you aren't too far away from your team as a result, but be on the look out for Hunters, as they will stop you from fighting back afterwards.
Pull will only affect Troopers, Rocket Troopers, and Hunters. Use it on the latter when unshielded, as it will prevent them from pressuring you into making a mistake and perhaps leading you into a hail of rockets and gunfire.
Your Cluster Grenades will cause no end of trouble for the Collectors, due to most foes being cluster together or fairly big but your lack of shielding leaves much to be desired. Play tactically with this class as you may otherwise end up downed quickly.
Charge should be used tactically too, since with what little shielding you have you will quickly find yourself vulnerable.
Pull is only effective against the Captains, Troopers and less so, Abominations. Be careful using said power against Abominations, as if you leave it too long you may end up pulling them towards you and/or your team, causing severe damage.