I loved Isle of the Nameless (GW1) for this; The Master of Damage was an excellent calculator; taking into effect even condition effects, with frequent updates as well. I could see the most general way my offense was taking effect with the Master of Damage. HotM just has some golems I can smash. Fun, but they don’t even last under a full zerker 100b.
I can’t see why this isn’t possible in the Heart of the Mists, unless the general murkiness of trait effects (do +% traits stack additive or multiplicative?) is actually a problem (I’m aware that they’re additive, but how’s a newer player going to know?).
Perhaps just set up a golem with champ-tier vitality and instant respawn who will calculate the rate of HP fall/time.