Opponents can not block and kill creatures you control.
Steps
At the beginning of your combat phase,
Helm of the Host triggers, creating a token copy of
Jegantha with haste that isn't legendary.
Activate the
Jegantha token 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 combat phases.
Infinite creature tokens.
Infinite ETB.
Infinite lifegain.
Infinite lifegain triggers.
Metadata
In 263 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).