Your search for "Hedron Detonator 31" revealed the following:
Hedron Detonator (MOC) from March of the Machine Commander, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Caroline Gariba Card Text:Whenever an artifact enters the battlefield under your control, Hedron Detonator deals 1 damage to target opponent.T, Sacrifice...
Hedron Detonator - Extended Art (MOC) from March of the Machine Commander, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Caroline Gariba Card Text:Whenever an artifact enters the battlefield under your control, Hedron Detonator deals 1 damage to...