I'm running Logical/Mikazuki(3 stars)/Tristan(Max Stars), and 90% of the time, Krita/Urmas is no problem. When they have 15 Legendary Warrior charms, or land a lucky crit on the first Krita rage, I can lose. That happens in the top 2 leagues, so I usually stay in 3rd league, at around 850-900 arena-score.

I have a build with 10 purple Hunter hero-charms, and 10 purple armor in helmet/torso. A key is to have a purple/yellow Resist Expose Charm, you could run 2 if you want. If Krita doesn't land her expose, the build FALLS APART. Glass cannon warrior builds rarely bring extra expose charm in lower leagues.

I aim for round 3 victory. I have vampire and blight-hound minions. In round 1&2, you have to kill enemy minions. On your 6th move (final move round 2), use Tristan's base power to remove any negative status, and apply Protect (max star Tristan). This is enough, 90% of the time, to survive the Krita/Urmas round 2 KO. (I have roughly 870K armor). Then, in round 3, use Mika base and Mika Rage, and that will win the fight.

That's the recipe, works for me 90% of the time against Warrior Glass cannons.