Final Fantasy IX gives us our number 1 spot on this list with the Izzet spell-slinger: Vivi Ornitier
In everybodys favorite casual format, where youre allowed to cast do-nothing 6-mana enchantments like Impostor Syndrome, there are plenty of ways to exploit this card, including legends-matter decks, blink decks, or decks that thrive on saboteur abilities
Its also important to note that Arwen gives counters to tokens as well, potentially giving you a huge boost in power
Haktos is just a dumb beater, and he gets shut down rather easily
However, in Commander, its especially good at either rushing your opponents, punishing them for playing more complex decks or just comboing off and suddenly winning the game in a single turn