The Headshot ability is a long range attack that deals physical damage to a single enemy unit. The attack has a high AP cost, preventing Luther from performing many more actions. When the ability is fully upgraded, Luther becomes a Sniper and shoots an explosive round which causes damage to all enemies in a small area.
The EMP Grenade is an area attack that deals magical damage to a group of enemies. This attack has a mid-range, making it Luther's lowest ranged attack. Fully upgrading EMP Grenade turns Luther into a Saboteur , the area damage he deals is much larger and can also stun enemies.
Mercy, similarly to Headshot, is a physical damage attack which is usable over a long range. Mercy deal slow damage to a single unit, however, if the enemy unit dies, Luther regains Action Points. When Mercy is fully upgraded, Luther becomes an Angel of Death and receives a buff to his damage when he kills a unit with this ability.
Mark Target is a long range ability that lowers the target enemy's physical and magical defences, making them much easier to take down. When Mark Target is fully upgrades, Luther becomes a Sentinel, a unit that is able to further debuff a group of enemies in an area.