Activate Ashnod's Altar by sacrificing Phylath, adding CC.
When Phylath dies, Nim Deathmantle triggers, causing you to pay 4 to return Phylath from your graveyard to the battlefield and attach Nim Deathmantle to it.
When Phylath enters, it triggers, creating at least one creature token.
Activate Ashnod's Altar by sacrificing a creature token, adding CC.