Ranged spell
You or one nearby ally

Until the end of the battle (or for five minutes out of combat), the target becomes invisible until it attacks or uses some ridiculously flashy action.

High Arcana: The duration out of combat is 1 hour instead.

7th Level Spell: 
You can now target 1d3 nearby allies (including you) with the spell.
9th Level Spell: 
Creatures made invisible by the spell have a 25% chance of remaining invisible the first time (and first time only) they attack or get flashy.