Conviction of His'tuun is an aberration created with the sole intent of punishing those who worship "false gods". His'tuun is the only one that merits worship, and any who worships another should be shown the error of their ways. Permanently.
Conviction of His'tuun is a fight that has a slew of flavor opportunities between Sacred Sense, Tremble In Their Presence and Drown Out The Heretics. You can narrate the eyes flashing, Conviction's head snapping towards a creature highlighted by Sacred Sense, and an almost rabid rage coming over the behemoth. In a similar fashion, as a spell is cast of divine nature, Conviction roars out in defiance.
When a creature first sees Conviction, you can narrate their hairs standing straight up and everything in their brain giving off alarm bells. They should run. Immediately.
As for the combat itself, it's fairly simple. Conviction is intended as a bruiser, sent in to clear things out and make way for further turmoil. Use Charge to put combatants on their back foot, and isolate a creature. When Conviction focuses on a target, it will use its tentacles to brutally assault the creature.
Conviction of His'tuun doesn't have much of a personality - it is a mindless being, born entirely with the intent of "getting rid of the competition". It is hell bent on defeating worshippers of other faith, but once none remain it will try to convert creatures with its One of Us ability.
With One of Us, the creature is fully converted and cannot be brought back. They will behave exactly like another Devotion of His'tuun.
Devotion of His'tuun was created into this plane. Willed, almost. His'tuun needs its competitors removed, and that can only be done with Conviction.
With Conviction of His'tuun, a brutal combat theme hits the mark well. Conviction is creepy and unsettling, but more than anything else it is a threat that needs to be dealt with immediately or else. The Gwent: Homecoming Monster deck theme hits this mark!
