Dread Liliana (Cube)

Sacrifice creatures to boost other creatures, then bring them back from the graveyard to do it again!

Bring big baddies (Sheoldred, Whispering One, Massacre Wurm, Greater Gargadon) from your hand directly to the battlefield with Sneak Attack. They only last one turn there, but then there's other abilities that pull them from the graveyard back onto the battlefield. Can also use Liliana, Defiant Necromancer or Liliana Vess's ability to discard them directly to the graveyard, and then bring them back.

Mogg War Marshall, Krenko's Command, Siege-Gang Commander, Ophiomancer, Hordeling Outburst: Creates token creatures, ripe for sacrifice.

Dread Return, Recurring Nightmare, Liliana, Defiant Necromancer, Sheoldred, Whispering One, Exhume: Graveyard to battlefield. All of these are sorcery-speed, so cannot be used at the end of opponent's turn to avoid summoning sickness. Exhume can only be used once, but it's cheap. Dread Return can only be cast once, but then could be fed other creatures to get something back at a 3:1 ratio. Recurring Nightmare can be used over and over again (hence the name!). Sheoldred and Liliana's abilities can be reused over and over, if they can be brought out.

Viscera Seer (scry 1), Recurring Nightmare (swap creature), Carrion Feeder (+1/+1 token), Greater Gargdon (remove suspend time counter): Battlefield to Graveyard

Bonfire of the Damned, Malicious Affliction, Siege-Gang Commander, Sheoldred, Whispering One, Massacre Wurm, Magma Jet, Flame Slash, Gatekeeper of Malakir: Enemy removal

An ideal setup would be to Ophiomancer out and its snake token generated, plus Viscera Seer. At the end of opponent's turn, sacrifice the snake token to the Viscera Seer to scry 1. If you choose to keep that card on the top of the library, you know what you're about to draw as it becomes your turn. Then your upkeep happens and you get a new snake token. The new token doesn't have haste, so can't attack, but can be a blocker on opponent's turn and repeat the cycle. If Purphoros is out too, every time a snake token is created, opponent takes 2 damage too.

With only three mana needed, you can get out Mogg War Marshal (WM; creates 1 token) and Recurring Nightmare (RN). In an opponent's end phase, sacrifice the WM to RN's ability to bring back another creature (or just don't pay the echo cost, so the WM dies; 2 tokens now). On your turn re-cast RN and sacrifice one of the tokens to it (1 token left) to bring back the WM (2 tokens now), and repeat. The next turn, don't pay the echo cost and WM dies (3 tokens now), re-cast RN, sacrifice a token to it (2 tokens left) and bring back the WM (3 tokens now). Each cycle is a net gain of one token. If you can get out the Siege-Gang Commander (needs 5 mana, or 4 using Sneak Attack), this cycle is more effective since he creates 3 tokens rather than 2.

Siege-Gang Commander, Massacre Wurm, Mogg War Marshal, and Geralf's Messenger have "enters the battlefield" triggers, which would happen even when bounced from the graveyard.