Guild Wars 2

Na its basically a mob being Invulnerable if you try to attack it from above. It happens a descent amount.

heres some threads about it Invulnerable Mobs in different scenarios.
https://forum-en.gw2archive.eu/forum/game/suggestions/Invulnerable-Mobs-Suck
https://forum-en.gw2archive.eu/forum/support/bugs/Mobs-suddenly-turning-invulnerable-and-regenerating-to-full-health/

if they just removed it…. but people would exploit its removal or something.

Botters everywhere! They have names like someone put a little 4 year old and let him punch some keys on the keyboard. For example the picture below, Qwehasd and Sdasdqwe. I know there has been a ton of botter complaints and yes I know this is not where you report botters. I have an idea instead. More in-game GM’s. This game is only gonna get bigger for awhile. This means more botters. There are so many botters all you have to do is play like 30 minutes and BAM!, there’s a bot. If we could semi-counter (yes, I realize the little significance more GM’s will have on the population of botters, but we have to do something) the army of immoral gamers, I would feel better.
ALSO where is the report player button??? I mean seriously.

Your name dude. xD
Range weapons in this game have to be improved. Shortbows can’t be used to range enemies from above, for example standing on a building above an NPC, I mean let me cheat here a little and attack without being attacked back. Maybe this is just a fantasy of a noob.

There is no right way to level, you just do what you feel is comfortable.