Sustained Invisibility

You craft an invisibility spell that maintains itself without constant input. 

A willing creature you touch becomes invisible until the spell ends.  Anything the target is wearing or carrying is invisible as long as it is on the target's person.  The spell ends for a target that attacks or casts a spell.  You can use your action to end the spell early on  any number of its targets. 

At Higher Levels.  When you cast this spell using a spell slot of 4th level or higher, you can target one additional creature for each slot level above 3rd.