Whenever Tinybones deals combat damage to a player, you may cast target nonland permanent card from that player's graveyard, and mana of any type can be spent to cast that spell.
Suit up a tiny deathtouch skeleton with evasion, connect for combat damage, and steal opponents' best permanents straight from their graveyards—using any mana to cast them. You grind value off everyone's dead creatures and artifacts while a stax/discard shell keeps the table low on resources.
One-mana commander that's cheap to recast and immediately threatening with deathtouch
Steals opponents' bombs, ramp, and removal magnets for free without paying their costs
Mono-black gives access to elite tutors, discard, and recursion
Deathtouch makes it a strong blocker and lets it trade up in combat
Tiny body needs evasion/protection to reliably connect
Trigger depends on opponents having permanents in graveyards—dead vs. graveyard-light decks