Mirror Box 
Artifact
The "legend rule" doesn't apply to permanents you control. Each legendary creature you control gets +1/+1. Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL