Activate Workhose by removing all +1/+1 counters from it, adding at least ({C} magic symbol) ({C} magic symbol) .
Workhorse dies as a state-based action due to having 0 toughness.
Othelm triggers, untapping itself.
Activate Othelm by paying ({2} magic symbol) and tapping it, returning Workhorse from your graveyard to the battlefield tapped with four +1/+1 counters on it.
Activate Workhose by removing all +1/+1 counters from it, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .