Probe Droid

Whenever one or more cards are put into any graveyard from anywhere, you may put a +1/+1 counter on Probe Droid.

Whenever Probe Droid deals combat damage to a player, surveil 1.

{1}{b}{r}, Sacrifice another Droid: Return Probe Droid from your graveyard to the battlefield tapped.

"Every secret stolen strengthens the machine."