Valduk has at least seven Auras and/or Equipments attached to it.
An opponent cannot block and kill Hellkite Charger.
Steps
At the beginning of your combat phase, Valduk triggers, creating at least seven 3/1 Elemental creature tokens with trample and haste.
Declare Hellkite Charger as an attacker, triggering its ability.
Holding priority, activate Thermopod's second ability seven times by sacrificing seven Elementals, adding seven ({R} magic symbol) .
Resolve the Hellkite Charger trigger, causing you to pay ({5} magic symbol) ({R} magic symbol) ({R} magic symbol) to untap all attacking creatures you control and causing you to get an additional combat phase after this one.
Repeat each combat phase.
If Valduk has at least eight Auras and/or Equipments attached to it, this combo nets infinite Elemental tokens and colored mana.