Volo triggers, copying the Deep Forest Hermit spell.
Resolve the copy of the Deep Forest Hermit spell.
When the token Deep Forest Hermit enters the battlefield, it triggers, creating four 1/1 Squirrel creature tokens.
Resolve the original Deep Forest Hermit spell.
When the nontoken Deep Forest Hermit enters the battlefield, it triggers, creating four 1/1 Squirrel creature tokens.
Activate Phyrexian Altar seven times by sacrificing the Deep Forest Hermit token and six Squirrels, adding 4.
Activate Temur Sabertooth by paying 1, returning Deep Forest Hermit to your hand from the battlefield.
Repeat.
This clever loop relies on Volo, Guide to Monsters to double your entry point, utilizing Deep Forest Hermit's unique type to trigger a spell copy without any type overlap in play or your graveyard. When both the original Hermit and its Volo-created token enter the battlefield, they flood the board with eight 1/1 Squirrel tokens that immediately receive a +1/+1 buff from the Hermit's passive anthem. You can then feed Deep Forest Hermit itself along with six of those Squirrels into Phyrexian Altar to generate the exact mana needed to fuel Temur Sabertooth's activation, bouncing the original Hermit back to your hand so you can recast it and start the whole cascade over again.