Activate Kenrith's fifth ability by paying ({4} magic symbol) ({B} magic symbol) , returning Avenger of Zendikar to the battlefield from your graveyard.
When Avenger of Zendikar enters the battlefield, it triggers, creating at least four 0/1 Plant creature tokens.
Activate Phyrexian Altar five times by sacrificing Avenger of Zendikar and four Plants, adding ({4} magic symbol) ({B} magic symbol) .
Repeat.
If you control five or more lands, this combo nets infinite creature tokens and colored mana, which can be used to activate any of Kenrtih's other abilities.
Results
Infinite +1/+1 counters.
Infinite card draw for any number of players.
Infinite colored mana.
Infinite creature tokens.
Infinite death triggers.
Infinite draw triggers for any number of players.
Infinite ETB.
Infinite lifegain.
Infinite lifegain triggers.
Infinite LTB.
Infinite sacrifice triggers.
Put all creature cards from all graveyards onto the battlefield under your control.
Infinite draw triggers for any number of opponents.