monkey d luffy one piece card game ST10-006 SR D. 7 Power Ichiban Kuji (A Prize): One

Reducing multiple enemies while removing another makes him one of the cleanest answers in the game, and his legendary status adds weight to every pull

It destroys anything at instant speed for three mana save for lands and just leaves them 1/1 grounded Human in exchange

A super cheap commander that scales so well with the game is quite powerful

This planeswalkers +2 loyalty ability turns simple artifact tokens or sac fodder like Ichor Wellspring into reliable card draw each turn

All the other Arena-exclusive cards could very well have cardboard counterparts if Wizards wanted, which makes them pretty inconsequential to the discussion