Rith, the Awakener + Breath of Fury + Phyrexian Altar + Concordant Crossroads
Rith, the Awakener
Breath of Fury
Phyrexian Altar
Concordant Crossroads
Infinite colored manaInfinite combat damageInfinite combat phasesInfinite death triggersInfinite creature ETBInfinite creature LTBInfinite mana creatures you control can produceInfinite creature sacrifice triggersInfinite untap of creatures you controlInfinite creature tokens with haste
How it works
Deal combat damage using Rith and the creature with Breath of Fury attached, triggering Rith and Breath of Fury.
Resolve the Rith trigger, causing you to pay 2 to create at least four 1/1 Saproling creature tokens.
Resolve the Breath of Fury trigger, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to a Saproling token, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Move to your next combat phase, and deal combat damage using Rith and the creature with Breath of Fury attached, triggering Rith and Breath of Fury.
Holding priority, activate Phyrexian Altar three times by sacrificing three Saprolings, adding 2.