Tactical Scan can be used to not only eliminate Atlases, but, if placed on a Phantom, also show where a cloaked Phantom is hiding.
If the Area Scan evolution is chosen, it allows for easy headshots of Guardians since it displays them in a similar manner to Hunter Mode. It can also be useful for finding cloaked Phantoms without having to target them with it.
Arc Grenades are incredibly effective against Cerberus troops, as they can remove the shields from Centurions, Nemeses, Phantoms and Atlases with ease - it is therefore recommended to equip the Grenade Capacity gear in order to be able to spam these for a long period.
Quarian Infiltrators should not be the first class to choose in battle against the Collectors, since they only have one offensive power, Arc Grenades, and they can only be effective against either armor or barriers, not both.
It is best to equip a weapon opposite of what Arc Grenades are evolved to do. (Assault Rifle and SMG when used against armor, and Shotgun, Sniper Rifle, and Heavy Pistol when used against barriers.)
The best enemy to use the Male Quarian Infiltrator against, as Arc Grenades can kill entire groups of enemies with ease, even on gold, since they have such a large area of effect.
Arc Grenades can easily be used to remove the shields from multiple Geth Hunters at one time and therefore make them all visible, which is very valuable on gold as Hunters are much more deadly.
The Tactical Scan evolution Area Scan can also be used to reveal where Geth Hunters are - however, its effects wear of quickly.
Tactical Scan can be used to fantastic effect on Geth Primes - it allows a player to then easily strip its shields with Arc Grenades, and then to kill it with a few sniper rifle shots from Tactical Cloak.
However, having all of the non passive powers and Quarian Defender upgraded leaves the player very vulnerable to attack. On gold, a player will die after two hits from a Geth Prime's cannon.
Tactical Scan works wonders against the armored units that Reaper forces possess - when used in tandem with Arc Grenades, a player can strip the barrier of a Banshee and then use a sniper rifle to finish her off.
However, Arc Grenades are less useful against all other Reaper units, so it might be a good idea to invest points elsewhere.