Activate Thermopod's second ability by sacrificing Optimus Prime, Hero, adding ({R} magic symbol) .
When Optimus Prime, Hero dies, its second ability triggers, returning it from your graveyard to the battlefield as Optimus Prime, Autobot Leader.
Activate Antler Skulkin by paying ({2} magic symbol) , giving Optimus Prime, Autobot Leader persist until end of turn.
Activate Thermopod's second ability by sacrificing Optimus Prime, Autobot Leader, adding ({R} magic symbol) .
When Optimus Prime, Autobot Leader dies, its persist ability triggers, returning it from your graveyard to the battlefield as Optimus Prime, Hero with a -1/-1 counter on it.