Tyra's burn monster talent does roughly 11.7% damage every .6 seconds. When Raum has his complete soul armor, that's 8k health. Tyra with burn monster does about 936 damage every .6 seconds, and that's not including weapon shots. Enough said.
Pick up resilience for heavy blade, or it'll slow you for 3 seconds. You could also pick up someone like Atlas who can catch the heavy blade, someone like Zhin/Koga who can cleanse the slow, or someone like totemic ward Grohk to prevent the slow.