Sting

You should go for yellow/yellow/green with Akam and Rezar as trainers. He is very fast to get started, causes a decent amount of damage as a striker. And if you position the green gems correctly, you can also recycle not too badly. Just his health status of course is not that great which can be a problem against top guys who you can‘t finish quickly, but cause a lot of damage themselves.

But for a pretty common character, Icon Sting is definitely a good choice to win most battles quite easily.

btw: you should check Haven tier list which gives you an idea of what movesets and trainers can be used best. If you want to dig even deeper, check out Guersan‘s videos.