Idea: Mirage

Mirage causes all units within a screen to turn into X

X being an ally, enemy, or even a random neutral creep

only affect the monitor of affected hero(es)

changes the targettability of all units within the screen, as well. for example, if all units is turned into enemies, then a laguna can be casted on them, however, no damage will be dealt, as they are actually allies.

or if all units is turned into a random allied hero, then no single target attack-type spells can be casted on enemies. AoE skills will damage them just fine, however.