A random match up, starting 50 yards apart in the parking lot of Arrowhead Stadium. No bystanders are present, but they left their cars while fleeing on foot. Both Jack of Hearts and Ikaris are in character, no prep. Win by incapacitation or death, no bfr.
I think this is a good match-up. I'd lean towards Ikaris, who has a wider range of powers, especially when it comes to telepathy, illusions, etc. He's also far stronger physically. But if you take it just as an energy-blasting/durability battle, it's probably pretty even.