None of the involved permanents have summoning sickness.
Opponents can not block and kill creatures you control.
Steps
Declare
Najeela,
Ahn-Crop Champion and
Jegantha as attackers, choosing to exert
Ahn-Crop Champion as it attacks.
Ahn-Crop Champion and
Najeela trigger.
Resolve the
Ahn-Crop Champion trigger, untapping all other creatures you control.
Resolve the
Najeela trigger, creating a 1/1 Warrior creature token that's tapped and attacking.
Activate
Jegantha by tapping it, adding ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) that cannot be spent to pay generic mana costs.
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 each combat phase.
Results
Infinite creature tokens with haste.
Infinite combat phases.
Infinite creature ETB.
Infinite lifegain.
Infinite lifegain triggers.
Metadata
Bracket tag
ExhibitionBracket 1+
For any deck
1
2
3
4
5
1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.