Whenever you cast an instant or sorcery spell, flip a coin. If you lose the flip, return that spell to its owner's hand. If you win the flip, copy that spell, and you may choose new targets for the copy.
Partner (You can have two commanders if both have partner.)
Krark turns every instant and sorcery into a coin-flip lottery: lose and you get the spell back to recast, win and you copy it. You build a low-curve spellslinger deck loaded with cantrips and copy/flip payoffs, then chain spells that net card advantage or burn until a flip-doubling engine snowballs into lethal. Most lists pair Krark with Sakashima of a Thousand Faces to copy Krark himself and stack flip triggers.
Effectively free spell recursion—losing the flip just hands the spell back
Huge value upside copying card draw, burn, and removal
Cheap (MV2) and partner-enabled for strong two-commander synergy
Krumar/coin-flip payoffs and rerolls make the variance lopsidedly in your favor
Excellent in a tight mono-red spellslinger shell
Inherently variance-dependent without flip-fixing cards
Mono-red lacks counterspells and clean enchantment/artifact answers
Krark gets removed easily and triggers stop
Can be a non-bo with X spells or spells you don't want bounced
Vulnerable to graveyard/hand disruption and fast combo decks
A copyable storm payoff that Krark turns into a lethal finisher after a long chain.
Add flip-fixing redundancy (Krark's Other Thumb, Frenetic Efreet, Mirror-style rerolls) so wins beat variance, plus cost reducers like Birgi and Goblin Electromancer to chain spells. Lean into a dedicated combo line—free spells (Mana Geyser, ritual loops) with Aetherflux Reservoir or storm payoffs—and run Sakashima to double Krark itself. Tighten the curve with efficient cantrips (Ponder-style red draw, Wheel effects) and protect Krark with cheap haste/recursion to maximize triggers.