Charnelhoard Wurm and Grand Warlord Radha on the battlefield.
You control at least two additional creatures that do not have summoning sickness.
Charnelhoard Wurm does not have summoning sickness.
An opponent cannot block creatures you control.
Steps
Declare Charnelhoard Wurm, Grand Warlord Radha and at least two other creatures as attackers.
Grand Warlord Radha triggers, adding at least ({R} magic symbol) ({R} magic symbol) ({RG} magic symbol) ({RG} magic symbol) .
Deal combat damage to an opponent using Charnelhoard Wurm.
Charnelhoard Wurm triggers, returning Relentless Assault from your graveyard to your hand.
Cast Relentless Assault by paying ({2} magic symbol) ({R} magic symbol) ({R} magic symbol) , causing you to untap all creatures that attacked this turn and to get an additional combat and main phase after this one.
Repeat.
If you attack with at least three additional creatures, this combo nets additional mana.