Excess Damage Lethal damage is the exact amount of damage you have to deal to kill a creature, planeswalker, or battle. It takes into account previous damage dealt to the permanent during that turn, so if you Lightning Bolt my Sheoldred, the Apocalypse, then a Shock would be enough to deal lethal damage (and the same would be true for a planeswalker or battle with 5 counters)
Annoying the crap out of people
Though not technically rabbits, I'm also going to take a look at some commanders that might be helpful to run as commanders in a rabbit-themed deck
Untap effects like Thousand-Year Elixir, Seedborn Muse, and Tyvar, Jubilant Brawler turn the Night Witch into an engine by letting you activate it multiple times a turn cycle, plus all that sacrificing pairs well with Midnight Reaper
But if you really think about it, there are actually some interesting use cases in Commander
Death By Clues Seven mana is always expensive, but turning all your Clues into win conditions and running over your opponents is a fantastic exchange