Probably unfixable invulnerability issue with freshly-spawned mobs

[srmalloy]

While running around a building in south Kallisti Wharf with my Fire/Dark Brute hitting up the doors for ToT mobs to beat down, I discovered what I think is going to be an unfixable synchronization issue between the server and the client.

 

I'm sure everyone who's participated in ToT at one of the 'murder motels' has seen mobs coming out a door getting hit with an AoE right as they emerge and popping "UNAFFECTED" above their heads, taking no damage (synchronization appears to let them make attacks while still being invulnerable, which is an entirely different issue, and also likely unfixable). When I'm running a character around solo for ToT, I always wait a second after they emerge before attacking, so ensure they're vulnerable to attack, and I don't waste End. With a character that has a PBAoE damage aura, the damage from the aura is an indicator of vulnerability, making it easier to judge.

 

What I found was that I could get a 'TRICK' spawn from a door, have them pop out of the door, see damage numbers from the character's damage auras float up from them, and unleash Fire Sword Circle... and get 'UNAFFECTED' from the entire spawn -- doing damage from the character's PBAoE auras, but unable to damage them with an attack after seeing the aura damage. I'm pretty sure this is a synchronization issue, and not something that's fixable with a code change, and it's a particularly odd corner case that I don't think is worth digging for -- there is a similar effect in the various invasions (Rikti, Nemesis, zombie), although in that case it's the mobs sometimes being targetable even before they become visible while not being attackable until after they've made their first attack  (while targeting through a pet will let you attack mobs that haven't even spawned in yet, another synchronization quirk).

Edited October 8 by srmalloy