When Whitemane Lion enters the battlefield, it and Arahbo trigger.
Resolve the Whitemane Lion trigger, returning it from the battlefield to your hand.
Resolve the Arahbo trigger, creating two 1/1 Cat creature tokens.
Activate Phyrexian Altar twice by sacrificing the Cats, adding 1.
Repeat.
This charming feline loop uses Arahbo, the First Fang to turn a self-bouncing visitor into an endless engine, amplified exponentially by Anointed Procession to double your token yields. By casting Whitemane Lion, you trigger Arahbo's ability to spawn a pair of feline tokens instead of just one, which you can immediately feed to Phyrexian Altar to generate the exact mana needed to cast the Lion all over again.