Regeneration [Limited Edition Beta] Ninth Edition Scholars say that arbiters exist

Scholars say that arbiters exist on every world

Whenever you tap a land for mana

destroy target creature with a -1/-1 counter on it

Set: Limited Edition Alpha Type: Creature — Elemental Rare Cost: {2}{G}{G}{G}{G} Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking

A keepsake for Vraska

Regeneration [Limited Edition Beta] Ninth Edition Scholars say that arbiters existSet: Limited Edition Beta Type: Enchantment Aura Common Cost: {1}{G} Enchant creature (Target a creature as you cast this. This card enters the battlefield attached to that creature.) {G}: Regenerate enchanted creature. (The next time that creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)