Does Immortal Phoenix have an additional cost or alternate cost, and would it work with the new purple Ezreal?

Ruling: Immortal Phoenix does not have an additional cost or alternate cost. Purple Ezreal only reduces optional additional costs (like Accelerate), so it does not work with Immortal Phoenix or Flame Chompers.

Nuances:

• Immortal Phoenix's "spend 1 power to play" is technically a cost within instructions, but not an "additional cost" because it doesn't explicitly say "as an additional cost"
• Purple Ezreal reduces optional additional costs only
• Deflect is functionally an additional cost in the rules, but purple Ezreal does not reduce Deflect costs because Deflect costs are not optional