I played a match (The first colosseum campaign, 2nd level, matchup with the goblin hunk, dwarf warrior and 2 zombies). I was terrified of Festering Guts while kiting the last zombie with my wizard, and waited until the duration had ended and the card disappeared to finish it off. Before dealing the killing blow, I saw that the effect card for FG was gone from the enemy model and right-clicked the model to be sure there was no listed effect. When I killed the zombie that turn, the Festering Guts triggered and blew me up
I'm still a fresh beta tester, is that as intended? I had thought it was the kind of buff card that needs to be played.
I wonder about that myself. Sometimes, I'm delighted/frustrated to move before my opponents move, because they haven't had the time to play their Traits (and draw new cards, which can include yet more Traits). Other times, cards jump out from their hand and make me go "Oh, yay, going first made things HARDER on me 'cause I didn't see it coming." I think confusion would be minimized by forcing BOTH sides to play ALL Traits before normal play begins. This would have the advantage of also finalizing replacement card draws.