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 Adept strikes at enemies with a biotically-charged fist.
Acrobatics - The Drell Adept rolls to quickly evade incoming attacks and flips over obstacles.
After maximizing speed in fitness and cluster grenades the drell adept/vanguard can be used as a strike fighter. Running from ammo box to ammo box. If while traveling you keep your eye open for groups of enemies to toss cluster grenades at and distracting large groups of enemies or simply attacking specifically the larger opponents letting the rest of you team mop up the stragglers. This can be greatly improved with adrenaline mods allowing you to move at blurring speeds. A team of biotics or even just using reave with the cluster grenades can create massive biotic explosions. Stick to hit and run on groups or large enemies, using your grenades as your main attack. Not effective with soldiers or other grenade users as they burn up extra ammo.
Drell start off with the weakest barrier of all Adepts and, as such, should try to stay in cover - this can be lessened by maximising the damage reduction given by Reave (so that it is 40%) and by fully evolving Fitness to maximise barrier strength and movement speed, which can get you out of sticky situations quicker, saving your life.
Their innate movement speed bonuses (faster than nearly any other class) greatly support a fully-standing, hit-and-run-tactic fighting style. When you find enemies, find tall cover to get behind, then strafe out of cover enough to get a sight on an enemy and use a power or shoot, before popping back into cover instantly.
The easiest way to set off a Biotic Combos is to use Reave on any enemy and then throw a cluster grenade at them. The main draw-back is the lack of ammo supply for grenades. In a crucial situation, an under-used Thermal Clip Ammo Pack can refill the players grenade supply.
An alternate, less reliable way is to use Pull and follow up with either Reave or Cluster Grenades (the former being far more reliable and easier to replace). This will cause a Biotic Explosion but can only be used on unshielded enemies that don't have armour. If you plan on using this tactic more than the Reave-Cluster Grenade combo, an SMG or Assault Rifle is the suggested weapon-of-choice, as barrier/shield protected enemies are the bane of its usage and SMGs/ARs are the most effective against shields and barriers.
As Cluster Grenades spread out, they become less accurate at range. They should be saved for when the player is near a group of enemies who can be hit by them easily, as they explode on contact. At this range, wounded enemies can easily be finished off with a shotgun.
If one has weapons upgraded enough, one can have the Acolyte as one weapon, and a moderately bulky weapon such as the Mantis, or the Valiant one can maintain over 100% cooldown, and while this will slightly affect Reave, Pull remains relatively unaffected if recharge speed is picked at Rank 6. Pull's can be used every 1.5 seconds with this setup while Reave can be done roughly every 3.4 seconds. This means you can still play like an Adept, but have the advantages of being able to use a gun to pick people off, or strip shields and barriers away.
Pull will remove Guardians shields, exposing them to weapons fire from all sides.
On low levels, Cluster Grenades can eliminate whole groups of weaker enemies if allowed to spread out, or individual heavy enemies if they all strike the same target.
Reave WILL hit Guardians through their shields, but it means damage is restricted for the rest of your team. It wont prove that useful when your friends are alive, but when you or only one other person is alive, this can prove invaluable since you can get multiple enemies with Reave, or you can focus your attention on more serious threats.
Cluster Grenades can be used to excellent effect against Reaper units, due to their tendency to bunch together, and their slow moving nature. This allows the full effect of Cluster Grenades to be used.
Pull, when fully evolved, can kill Husks in one go and can be rapidly used, allowing a player to defend themselves at close quarters.
Use of Reave is highly recommended against Banshees, since their Biotic powers will quickly strip you of your barriers and your health. Reave will lessen this damage somewhat. It will also help protect in general if enemies focus their attention on you.
Reave is very effective against Geth Hunters, as it illuminates them, allowing the player to see them easier and putting them on the AI's auto-target radar. This allows powers to target them automatically, rather than manually. If the Hunter can't be targeted due to auto-target using Reave on a different enemy, the player can choose the Rank 4 Area of Effect evolution and target the nearest enemy, assuming the player is within 3 Meters of the Hunter. The Hunter will then be affected by the AoE damage, allowing them to be targeted by other powers.
Once Troopers, Rocket Troopers, and Geth Hunters are unshielded, you can Pull them. Then said enemies are at your mercy.
Using Pull on Abominations is questionable at best since they explode after death, if you do decide to pull said foes, make sure you are at a generous distance. This will ensure you have plenty of time to dispatch them, because if you leave it too long they will detonate after death which will deplete what little shields the drell already has.
Reave is very useful against Praetorians, since the ability is instant, it can go through the protective shield that the Praetorian sometimes puts up.
Cluster Grenades are strongly encouraged to take out large groups of trooper level enemies like Abominations, or Collector Troopers.