, , Sacrifice another creature: Brion Stoutarm deals damage equal to the sacrificed creature's power to target player or planeswalker.
Brion Stoutarm is a fling-on-a-stick commander: ramp into a single massive creature, then sacrifice it to deal its power directly to an opponent's face while gaining that much life. You assemble big bodies (or temporarily steal opponents' creatures), throw them for huge chunks of damage, and use lifelink plus the lifegain to stay safe while you set up lethal hurls.
Inevitable burst damage that ignores blockers and goes to the face
Lifelink and the sacrifice lifegain make you very hard to race
Throwing stolen creatures gives a built-in answer plus a finisher
Boros has excellent ramp, equipment, and big-creature support
Heavily commander-dependent; removing or taxing Brion stalls the whole plan
Color identity lacks card draw and ramp depth compared to other colors
Only one activation per turn without untap effects, so it's slow without enablers
Sacrificing your big threat into a wrath or counterspell can be a blowout
With ritual mana it grants infinite combats, and more relevantly extra untaps for repeated Brion activations.
Add untap enablers like Aggravated Assault, Thousand-Year Elixir, or Aurelia to get multiple flings per turn, and cheap power-doublers to turn a single hurl lethal. Lean into ways to reliably produce a huge body fast—Sneak Attack, reanimation like Reya Dawnbringer effects, or +X/+0 anthems—plus protection (Boros Charm, Teferi's Protection) so a board wipe doesn't ruin your plan. Improve consistency with strong Boros ramp (Smothering Tithe, Boros Signet, Skullclamp for card advantage).
Legendary Creature — Giant Warrior
, Sacrifice another creature: Brion Stoutarm deals damage equal to the sacrificed creature's power to target player or planeswalker.