Can only target air units.
Can only target alive units (non-skeleton).
Can only target allied units, but not units on the same team as casting unit.
Can only target ancients i.e only the night elf buildings that can uproot.
Can only target dead units (corpses, skeletons).
Can only target debris, e.g crates.
TODO: unknown what this target allows.
Can only target enemy units.
Can only target allied and own units.
Can only target units without flying/hover movement type.
Can only target hero units.
Can only target invulnerable targets.
Can only target items lying on the ground.
Can only target mechanichal units catapults etc.
Can only target units which belong to neutral players (Neutral Hostile, Neutral Passive)
Can only target non-ancient units.
No targets allowed.
Can only target non-heroes.
Can only target non-suicidal units.
Cannot target casting unit.
Can only target non-mechanical units.
TOOD: this is unknown what it does.
Only able to target units from the same player as casting unit.
Can only target suicidal units such as Goblin Sapper.
Can only target caster.
Can target buildings.
Can only target landscape such as grass, water or dirt.
Can only target trees.
Can only target units that can take damage.
TODO: uncertain if this limits valid targets to gates.
Limit to units which are wards (Statis Traps, etc).