These still see through double invis or invis and ivu. a blood bat They are mixed in with the undead area of LI and would make sense to be either undead as "vampyre bats" or live in which case one of the two invis types should work against them. As no undead spells work on them, I believe they are flagged incorrectly, as that whole area was at the launch of LS.
What makes you think it's a bug? Lots of animals, particluarly bats, have always seen thru invis throughout EQ's history.
Echolocation They don't need to see you to find you (hence invis doesn't work on them) (or for the dnd nerds Blindsight)
Because all the undead in the same location saw through both invis and itu at the launch of LS. Lots of bugs make it through and persist if not reported. Until it is confirmed "Not a bug" and a design choice.
The only undead that I noticed that saw through ITU on lauch day were the named mobs. Maybe you ran into "a spectre" which, by it's name, doesn't really imply it's a rare mob.
It makes sense that bats would see both, they don't "see" as other creatures do, they bounce sound off objects.
Just like those fun bats in CoV's Dragon Necropolis seeing SoS. Before the body type changes. That was a fun surprise when sneaking around for shinies lol. Lesson re-learned. Con everything from the front.
I'm saying when large sweeping things make it through beta and test and go live and the EQ communities clamors "not a bug!" ...doesn't make it so. You can check my track record if you like. The undead at launch 100% were not flagged correctly and saw through both ITU and Invis. The fact that the one model in the same area still works that way could be explained by an oversight...or working as intended. But no player can say working as intended with 100% certainty. Look at the recent anniversary type 3s. On test you could only get one, I reported it as bugged, not likely to be well received due to the release of personas....and it got changed to lore equipped. Just because it "isn't a bug" doesn't mean it makes sense to leave in the game.
Bats normally see through all invs if you look at older expansion though so it seems normal that they would in new expansions. Plane of shadow and shadow valley they see through so why not in LS? Given I won't say it isn't bugged, there is always the possibility they missed bats in older expansions that should be able to see through invs and couldn't due to a bug (I know of some bats that can't see through invs).
Bats in Dragon Necropolis (CoV) see through rogue SoS as well, as was intended when the expansion launched.
I could go through all the mobs labeled "bat" in EQ history and there would be far more that don't see through invis.... using other mobs may not be the strength you think it is. Including mobs in the LS expansion, like "a bat" in Unkempt Woods that does not see invis, "a moors bat" in Moors of Nokk as well. If anything that logic makes more sense that "a blood bat" in LI would be an undead mob and only see invis and not ITU.
It must be a vampire not a bat! There is no such thing as an undead bat but there could be a vampire in bat form!
My overall point is that it appears bugged, coded incorrectly to see through both ITU and invis, much like the undead in the same area were at the launch. It's either a live bat and should see through ITU or it's an undead bat and it should see through invis, but seeing through both seems like remnants of the initial bug at launch.
Invisibility in most role playing games is not a "I cannot be detected at all by the enemy" spell.. Its the enemy cannot see me with their eyes spell (or in an undead's case they cannot sense my life force as well). If an creature has an alternate way of detecting you they should be able to locate you (its what real life bats do to locate their prey in the dark) But do you really want to walk down this path.. This argument really reminds me of the time someone adamantly complained about a certain pop glaze item being not flagged as tradeskill (unlike the rest), and because the person complained so adamantly they nerfed the rest of the similar tradeskill items instead)
Yeah, like that glaze, this is not the hill to die on. They screwed up enough mobs when they did the body type changes globally instead of just whatever zones the devs had an issue with. I don't want to see Body Type F-up 2.0. Just run around them like everyone else.