Specifically the ARAM brawl mode. I will list a tank, dps and support;
Tank - Stitches. Savour the flavour with double devour at 20… marvelous. (just finished a game with 50+ stacks of it, was bullying the enemy team back alone even when my healer was dead).
DPS - Valla. Pure Hatred build, never run out of mana, self heal and tons of damage.
Heal - Probably Deckard because you get so much value from his abilites.