Spend this mana only to cast a creature spell." Not bad, and certainly relevant in stompy Commander decks, but the real kicker comes in its other activated ability, which allows you to tap Herd Heirloom to grant a creature with power four or greater that you control trample and "Whenever this creature deals combat damage to a player, draw a card," until end of turn
With 64 options, thats 32,000 unique cards
During your opponent's next turn, this Pokmon takes 30 less damage from attacks (after applying Weakness and Resistance)
a Blade of Selves as "Clive's Invictus Blade"
If I hadnt been able to pick up multiple powerful cards to ramp into, then I would favor Mickey Mouse - Steamboat Pilot
Thanks goes to Steffenka for compiling the set list for this story