How does faction loss works?
 

I'm factionned in chardok and been buffing players/groups around entrance/CE and noticed when I buff them while in combat and their mob dies sometimes I lose faction and sometimes I don't. Like sometimes I drop a group c2 on them mid fight and I don't lose faction but sometimes I'll haste a melee and I'll lose faction. I checked the wiki and googled a bit but couldn't find anything.

Is it because if you buff and they don't take direct action toward the mob post buff you won't get hit? Like if mob is dotted and pet is on it and you buff shaman that only watches it die you're fine but if shaman reroots mob you're not fine anymore?

I thought you'd get a hit the second you interacted with a player getting a hit but apparently it is more nuanced. I'd run tests but my faction is getting low right now and I'd like to stretch what's left.

If someone has primary agro into a mob and you land a beneficial buff on them you will receive the faction hit. If they don't at the time the buff lands you won't. I know bard songs apply this logic to everyone in the group every time the song pulses. I can't speak to group buffs if it works similar to bard songs accross the whole group or only counts towards the person you cast on, not the other group members. That's the only nuance I can think of.

What do you mean by primary aggro?

If someone has already damaged / debuffed a mob and then you cast on that person then you should get a faction hit (unless the mob got memblurred in the meantime).*

If you cast on them and then later they piss off the monster, you should still be good.

*apparently there is some kind of check a mob might do where they have a chance of not noticing your assistance, but I dunno if that is implemented or in era.

Yeah that's what I thought so this is why I expected a hit for casting gift of pure thought on a cleric. Seen the particles transfer to the whole group, namely a paladin MT currently fighting and I got no hit. So I guess group buffs faction hits only affect target (cleric) and if cleric doesn't take part then you're fine?

Group buff dynamic could be tricky but I've dumped C2 on shamans in combat and sometimes I get a hit and sometimes I don't so I'm puzzled as to what exactly triggers a faction hit.

Primary Agro - I cast a hate inducing spell directly on the mob (some spells intentionally don't create hate/agro like lull/paci lines)
Secondary Agro - I root a mob nearby and the mob agros me.

Yeah getting faction hits off secondary (i.e. not engaging the mob directly but buffing someone) can be tricky. I never have an issue with it on bard (always get the hit) because songs touch everyone in the group but don't have a target and pulse every 6 seconds.

If you want to ensure that you're getting the faction hits (like if you bring a low level toon to kael and want faction without getting too close). I would recommending casting multiple times (if its a group buff, I would even rotate targets in the group) just to be sure.

If you want to avoid any faction hits I would zone out or feign death before the mob dies to be sure you don't take the hit.

Casting heals or beneficial buffs only have a chance to add you to the hate list. It is not guaranteed.

I don't think that's right. If a warrior is tanking a mob and you heal that warrior you will get all the same faction adjustments that the warrior does when the mob dies. This is the whole basis for rando priests healing the MT during faction pulls in kael and it always works. Only exception would be if somebody blurs it before it dies or something.

How many times did you heal? If it's only once, there's a chance you did not add to all of them. The more heals, tho, the more likely it is you did.

It is more apparent in the scenario proposed by OP where they only intermittently receive the faction hits when there's only a single pull in camp.