Barktooth Warbeard is a vanilla 6/5 for seven mana, so the deck builds around it rather than with it: use Rakdos's aggression and big-creature support to turn a beefy body into a Voltron threat or simply lean on the color pair for an interactive midrange game. Cast it cheaply via cost reduction or reanimation, strap on equipment and evasion, and crash in for commander damage. Otherwise, treat Barktooth as a sturdy figurehead while the 99 does the real work.
Big 6/5 body that's hard to kill with most chip removal and survives many board sweepers' damage thresholds
Access to Rakdos's elite removal suite and recursion
Cheap to acquire and unexpected, so it flies under opponents' threat assessment
Completely vanilla with no abilities or built-in evasion or protection
Seven mana for a body that doesn't impact the board on cast
Dies to single-target removal with zero value, and needs heavy support to threaten 21 commander damage
No card advantage engine attached to the commander itself
Legendary Creature — Human Warrior
