Activate Phyrexian Altar six times by sacrificing Gerrard and five other creatures, adding ({5} magic symbol) ({B} magic symbol) .
Gerrard dies, triggering its ability.
Holding priority, activate Kenrith's last ability by paying ({4} magic symbol) ({B} magic symbol) , returning Gerrard from your graveyard to the battlefield.
Resolve the Gerrard trigger, returning all artifact and creature cards put into your graveyard this turn to the battlefield.
Repeat.
Once you have infinite colored mana, you may use it to activate Kenrith's other abilities.
Results
Infinite +1/+1 counters.
Infinite blinking.
Infinite card draw.
Infinite colored mana.
Infinite death triggers.
Infinite draw triggers.
Infinite ETB.
Infinite lifegain.
Infinite lifegain triggers.
Infinite LTB.
Infinite sacrifice triggers.
Infinite card draw for any number of players.
Put all creature cards from all graveyards onto the battlefield under your control.
Infinite draw triggers for any number of opponents.