Activate Ashnod's Altar by sacrificing Myr Battlesphere, adding CC.
When Myr Battlesphere dies, Nim Deathmantle triggers, causing you to pay 4 to return Myr Battlesphere from your graveyard to the battlefield and attach Nim Deathmantle to it.
When Myr Battlesphere enters, it triggers, creating four artifact creature tokens.
Activate Ashnod's Altar by sacrificing a creature token, adding CC.