Slimefoot and Squee + Phyrexian Altar + Beetleback Chief

Slimefoot and Squee
Phyrexian Altar
Beetleback Chief

Requires
All permanents on the battlefield. You control at least one Saproling. 1 available, plus either b, r or g available.
Steps
  1. Activate Phyrexian Altar twice by sacrificing Beetleback Chief and Slimefoot and Squee, adding two mana in any combination of b, r or g
  2. Activate Slimefoot and Squee by paying 1brg and sacrificing a Saproling, returning it and Beetleback Chief from your graveyard to the battlefield
  3. When Beetleback Chief and Slimefoot and Squee enter the battlefield, their abilities trigger
  4. Resolve the Slimefoot and Squee trigger, creating a 1/1 Saproling creature token
  5. Resolve the Beetleback Chief trigger, creating two 1/1 Goblin creature tokens
  6. Activate Phyrexian Altar four times by sacrificing the two Goblins, Beetleback Chief and Slimefoot and Squee, adding 1brg
  7. Repeat from step 2
Results
Infinite ETB. Infinite LTB. Infinite death triggers. Infinite sacrifice triggers.