Sanctuary Wall is a uncommon Artifact Creature — Wall card from Murders at Karlov Manor (MKM), collector number 32. Current market price: $0.23 (foil $0.23), TCGplayer market prices via Scryfall.
Defender {2}{W}, {T}: Tap target creature. You may put a stun counter on it. If you do, put a stun counter on this creature. (If a permanent with a stun counter would become untapped, remove one from it instead.)