Crystalline Crawler has at least eight +1/+1 counters on it.
Bright-Palm does not have summoning sickness.
Bright-Palm and Hellkite Charger cannot be blocked and killed by an opponent.
Steps
Declare Bright-Palm and Hellkite Charger as attackers, triggering their abilities.
Resolve the Bright-Palm trigger, doubling the number of +1/+1 counters on Crystalline Crawler.
Activate Crystalline Crawler's first ability seven times by removing seven +1/+1 counters from it, adding ({5} magic symbol) ({R} magic symbol) ({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 to get an additional combat phase after this one.