Merfolk Tunnel-Guide 
Creature — Merfolk Wizard
When Merfolk Tunnel-Guide enters, you get a three-time boon with "Whenever one or more Merfolk enter under your control, target Merfolk creature you control explores."
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL