Whenever you sacrifice another creature, exile cards equal to its mana value from the top of target player's library. Until your next end step, you may play those cards, and mana of any type can be spent to cast those spells.
Sacrifice another creature: Rakdos gains indestructible until end of turn. Tap it. Activate only once each turn.
Sacrifice expensive creatures to exile and steal cards off opponents' libraries, casting their best spells with any color of mana. Use big mana-value sacrifice fodder (and ways to recur it) to dig deep into rivals' decks while keeping Rakdos indestructible and aggressive in the air. Grind value until you've stolen enough resources to bury the table.
Effectively plays cards from opponents' decks, giving you access to off-color bombs and removal
Color-fixing built in—mana of any type can cast the exiled spells
Built-in indestructibility makes Rakdos hard to remove and a steady evasive threat
Rewards a free sacrifice each turn, fueling aristocrats synergies
Punishes opponents twice: removes their resources and gives them to you
Needs a steady supply of high-mana-value sacrifice fodder to maximize the exile trigger
Sacrificing one creature per turn cap on the indestructible ability limits explosive turns
Card advantage is somewhat random—you cast what opponents happen to have on top
Vulnerable to graveyard and recursion hate slowing your sac engine
No inherent protection from being exiled or bounced, only indestructible
Recurring sac fodder that keeps coming back to feed the engine.
Add free sac outlets (Carrion Feeder, Viscera Seer) and recursion (Reassembling Skeleton, Gravecrawler) so you trigger Rakdos every turn, then load up on cheaply cheated high-MV creatures via reanimation (Reanimate, Animate Dead) to maximize cards exiled. Lean into Blood Artist-style drain payoffs and fast mana like Ashnod's Altar and Phyrexian Tower to convert sacrifices into wins, and tighten the curve with efficient interaction to protect your engine.