@Taisiakat
As you suggested, I did a straight swap out of my Hero (Y/P weapon) for Naga Queen which gave me this team:
Marilith
Poison Master
Scale Guard
Naga Queen
Abyssal Banner retained
4/40 souls won
x35 soul bonus displayed
Conversions applied correctly: Warlord4 x3.75 = 15 +20 = 35
So it does indeed appear to be that the Mist of Scales/ Naga perks of the Assassin Class are bugged and are causing this issue. Thank you for recalling the original reports and for pointing it out.
@Theicla sorry about that. I know that Assassin class KICKS butt… I play it when I am bored with Priest.
I was hoping it was fixed… But I guess we should report Assassin class now. Glad I was able to help 
So does a Hero Naga give snotstone as well?
I didn’t bother because I wasn’t sure, since the Hero Naga didnt count as event bonus.
Unfortunately it doesn’t, I just fought one 
. Not sure if it’s a known bug, tagging @Sirrian, @Nimhain and @Saltypatra just in case.
The Hero Class perks not counting as part of a Team of Naga and Mist of Scales are a bug, to be sure.
But yesterday they may have attempted to ninja hotfix the Assassin Hero itself to yield the +20 souls anyway when used in the Bonus Souls event (when you put your Hero in a team of Mist of Scales Naga).
Well, he does count as Naga from MoS for bonus purposes, just not for the Snake Eyes event.
On the other hand the perk says “Count as Naga for Team Bonuses”, so maybe that’s how it was intended. It’s counter-intuitive though if that’s the case.
That is a bummer, I placed a Naga Assassin in my D Team to give my opposition more Event Gems. Probably should switch him out for a “real” Naga but Assassin is just too good 
Well, that’s what I did. I try to field at least slightly challenging teams, but defence wins are unimportant (maybe not so much when you go for top 100 or better in PvP, but that’s still a “maybe”) and since anything challenging is pretty much impossible with Nagas only so be it.
No, 4 * Scale Guard isn’t challenging. It’s only annoying.
First of all thank you to everyone who has made Naga teams for defense in PVP.
But it is getting boring after day 2+ since it’s one of 4 of the 5 troops that can be used to make up a Naga team. Trying to figure the best way to quickly go through them. Sometimes we get lucky and it’s only 2 nagas, or the same naga, or pairs.
I almost went with my giant team for the heck of it since it does pretty good damage but just doesn’t hold up against poison well…
Btw, even the lower level teams, Nagas are pretty impressive for doing some serious damage.
Yeah it’s a known bug, but needs an update to fix it.
The team I’ve had the most trouble with so far this week has actually been a team of 4 Scale Guards fully Mythic-traited.
Same for me… because my power hitters are in the first two spots, which are also what the Scale Guards take out right away ><
This week’s event is a bitch. Can’t use challenges. Explore is giving 1 or none most of the time.
And very few people in my PVP tier are using anything but the typical Wraith / Bone Dragon garbage.
Which PvP tier are you in? Im getting avarage higher then 1 naga per battle. The same i was getting with giants basicly.
And it could be a lot higher the 1.3 per battle if i chose only the battles that have naga instead of always going for 3 trophies.
I’m level 1140.
I got a lot more giants than I’m getting nagas. About 1 in 4 of my offers have even 1 team with Naga and then that team generally has 1 token naga and the typical Bone Dragon / Courage setup.
I’m sure I could get more if I went to a 1-troop defense but then I’m hurting everybody who is invading against me.
And wouldn’t you know it, immediately after posting that I started getting a bunch more 4-naga teams. 
Is this generally working fairly well on PC/Mobile now? I mean, are a reasonable number of people actually putting up event-specific defence teams?
Now that we have events on console, I’m hoping that the practice spreads. In my first hour of event play, I only saw one person putting up a Mech team so aside from that, the only ones I’ve been able to find are Goblin Rockets and Deep Borers. I put up a mech team and hopefully others will get in the habit once they figure out the new system.
Some weeks yes, some weeks no. Honestly I think a lot of people just can’t be bothered with changing their defense team. Defense is almost an afterthought.
I actually have been pleasantly surprised by the number of Event Gem defenses I get on most weeks. Sure I’m getting a lot of 4x Scale Guards but nothing that my Assassin 
spam invade can’t handle. Sturdy traits actually are getting a workout for a change
My defense team rating is 9605 (its 4 nagas, but all my nagas are fully traited and fully leveled).
Im level 900. So we are experiencing different things. I am plesently surprised at how many players have put up nagas as their defense.
I have been too. Until this week. I’m getting them in spurts. I haven’t seen any in like an hour again now.