Belletrix wrote:
It's just one of the many insane powers that NPCs have. Just like being about to cast while there are 20 people hitting it, being able to cast on you from 3 miles away, wonderful pathing that makes them pop up behind you when you pulled them from right in front of you, can quad you for hundreds with their bare fists when you know the mob is a wizard.…..so why shouldn’t they all instantly grow gills and be able to swim like a fish? Haha
They are really "insane powers". They are things that the devs have to allow the NPCs to be able to do to compensate for the fact that no one has yet invented a really good AI.
If mobs couldn't swim, then you could simply float in the water a distance away and nuke/dot/bow them to death all day long with no risk to yourself. Kinda silly? Yup. So you have to allow them to go into the water.
If mobs can swim but also drown, then anyone with a sow and EB up could kill any number of mobs simply by agroing them getting them to follow them into a lake, and then running them around in circles under the water until they all drowned (which wouldn't take long given how drowning works). Huge exploit.
Most mobs can be interrupted when casting spells. Um. But some mobs certainly can cast spells with 20 people beating on them. You wanna know why? Because they are raid level mobs and there are going to be 20 people beating on them. Be kinda silly to give a raid level mob casting ability, but not give it some resistance to being interrupted. It's all about balance. Mobs designed for single groups to fight can generally be interrupted just fine.
All of these are things to prevent players from exploiting the game and the NPCs to trivialize encounters. Weird pathing or warping happens when the path from the mob to you is blocked. If the game allowed NPCs to get stuck in the environment, then you could once again easily kill them by trapping them in a corner and nuking them over and over. Instead, they will warp through walls and such to get around obstacles. Spell casting is the same. While a mob can't start casting a spell on you unless you are in range and in LoS, his spell will land on you no matter what range you are, or what's in between. This is also due to mobs not being smart enough (and players are). If that didn't happen, you could nullify a spellcasting mob simply by running around a corner whenever it stopped to cast. Mobs follow specific agro rules, so a mob will never deliberately run out of LoS to avoid a spellcast, players certainly will, so the rules have to not allow that.
Every odd bit of the game in terms of mob abilities generally has to do with ensuring that the mob requires some level of work/skill/whatever to defeat. Nothing really amazing about it.