An opponent cannot block and kill creatures you control.
You have at least four experience counters.
Steps
Declare
Otharri as an attacker.
Otharri triggers, causing you to get an experience counter and create at least five 2/2 Rebel creature tokens that are tapped and attacking.
Activate
Phyrexian Altar five times by sacrificing five Rebels, adding ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) .
Activate
Najeela by paying ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) , untapping all attacking creatures, giving them trample, lifelink and haste, and gaining an additional combat phase after this one.
Repeat.
Results
Infinite creature tokens with haste.
Infinite colored mana.
Infinite combat damage.
Infinite combat phases.
Infinite death triggers.
Infinite creature ETB.
Infinite experience counters.
Infinite lifegain.
Infinite lifegain triggers.
Infinite creature LTB.
Infinite creature sacrifice triggers.
Metadata
In 10 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).