It's awkward to read in hand, doesn't fit correctly on the stack, breaks a ton of visual effects that already exist, and is simply a case where the paper solution doesn't translate to digital ("just turn it sideways to read it" is fine for a card, but is not acceptable for someone's 49-inch ultrawide monitor, much less a smart phone)
I will say that quite a few different damage-doublers and life loss effects are floating around, all at varying converted mana costs, permanent types, etc
In a dedicated shell copying spells, however, The Twelfth Doctor gets big rather quickly, turning it into a possible win condition
Unlike many effects that grant additional combat phases, you don't get an additional main phase with Godo, Bandit Warlord's ability
Illustrated by Daarken Standard Not Legal Alchemy Not Legal Pioneer Legal Historic Legal Modern Legal Brawl Legal Legacy Legal Comp
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