You control at least five other creatures that can attack this turn.
Tesak does not have summoning sickness.
An opponent cannot block and kill creatures you control.
Steps
Declare Tesak, Hellkite Charger and at least five other creatures you control as attackers.
Tesak and Hellkite Charger trigger.
Resolve the Tesak trigger, adding at least 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 and to get an additional combat phase after this one.