Orcish Bowmasters dies, triggering Nim Deathmantle, causing you to pay ({4} magic symbol) to return Orcish Bowmasters from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Orcish Bowmasters enters the battlefield, it triggers, dealing 1 damage to any target, then creating a 0/0 Orc Army creature token and putting a +1/+1 counter on it.
Activate Ashnod's Altar by sacrificing the Orc Army, adding ({C} magic symbol) ({C} magic symbol) .