Activate Shilgengar by sacrificing Boonweaver Giant
When Boonweaver Giant dies, Kaya's Ghostform triggers, returning Boonweaver Giant from your graveyard to the battlefield
When Boonweaver Giant enters, it triggers, returning Kaya's Ghostform from your graveyard to the battlefield attached to Boonweaver Giant.
Resolve the Shilgengar ability from step 1.
Repeat.
This clever loop spins up endless artifacts and triggers by turning Boonweaver Giant into an infinite sacrifice engine, fueled entirely by the graveyard-recursion safety net of Kaya's Ghostform. Every time Shilgengar, Sire of Famine demands a creature to feed its hunger, sacrificing the Giant triggers the Enchantment to bring it right back, which in turn fetches the Ghostform back from the graveyard to reset the whole cycle. Shilgengar happily converts those repeated sacrifices into an endless tide of Blood tokens, effortlessly translating a single loop into infinite death and entry triggers for whatever catastrophic payoff you need.