Does Ezreal's ability to reduce optional costs work on cards with 'may' in their cost text, such as Draven's cost or Deflect?

Ruling: Ezreal only reduces "optional additional costs" - costs that say both "may" AND "as an additional cost." He does not reduce costs within instructions (like Draven's) or mandatory triggered ability costs (like Deflect), even if they contain "may."

Nuances:

• Draven's cost is a "cost within instruction" and is not an optional additional cost, even though it says "may"
• Deflect's cost is technically mandatory - what's optional is paying for costs incurred by triggered abilities (if you don't pay, the triggered ability doesn't happen)
• Ezreal does work with Accelerate and Repeat, as these say both "may" and "as a cost/additional cost"