Here is what I have ascended 4T:
Here is what I could ascend (in the order of ‘value’ I think they provide to my team)
RIP Magni – I ate him. Stupid? Sure. But at the time I was quitting and didn’t expect to ever get another scopes with Aegir & Raffaele ahead of him…
Current as of 01/25/21
Might be a weird vote, but I’d want to do Isarnia first, Aegir second. King Arthur already fills that Frida role on a Titan too well for me to want to go that direction. You already have Ariel to keep your titan team or blue stack alive, so Aegir is to me, less of a priority.
That leaves Isarnia, whose new costumed identity (should you have already or later obtain it) is pretty nasty with high attack and the defense down that will complement Arthur.
I mean… 869 BASE attack. Jeez.
May titans weep.
I’d recommend either Magni or Aegir, as already having Arthur’s ice-defense-down makes Frida’s largely overkill.
Magni is a great sniper who, because he charges so quickly, will almost always affect whatever fight you take him to; and Aegir is a game-changer when he goes off, which is—because of his defensive stats and average mana speed—more often than Isarnia.
To piggyback on @Gallowspider, if you’re able to get Isarnia’s costume, then definitely ascend her. But I wouldn’t hold my breath (or my scopes) waiting on that to happen.
My vote is Aegir.
Don’t really need a maxed Frida as you got Arthur who can do the defence down.
Aegir has a benefit of being a 5* damage sharer (very good on raids and titans) as well as a heal for damage (again very good when you have a blue stack going).
I take aegir to red titans and a single tile heals my entire squad for like 400-600 HP… Basically I never lose a hero against red titans anymore.
Added benefit you’ll have a very solid blue tank if your alliance uses blue tanks for AW.
Excuse me, why is Thorne not a choice in this bunk poll 
Personally, I’d go with Isarnia to add defense down to your roster. I mean, I don’t doubt you’ve got a maxed Grimm, but Isarnia’s debuff is much more powerful. & Adding the fact that you could one day pull her costume, which would permanently increase her stats, helps make that decision all that more simple (in my mind)
I mean I love Frida, and she’s more fun to use in raids [than Arthur] with a hit three and dispel three, but with already having Arthur maxed, I just don’t see a reason to max her solely for that.
& Magni is awesome too, but you already have a couple of snipers maxed in blue, so again, not as vital.
Then there’s Aegir, who makes a great tank and is alright on offense for survivability, but idk, unless you’re in desperate need for a solid tank, I think I’d put him on the back burner, too. Not a huge fan on him on offense, cuz even though he helps your team survive a little longer, the heal is so minor that I’m usually regretting the fact that I didn’t just bring a better healer with me, instead. & With him being 100% passive, you don’t get nearly as many benefits [maxing] as you would with any of your other options, considering the rest need to hit 80 (in order to max their attack stats) to be of the most use on offense [with their attacks].
So yeah, that’s my vote (and reasoning), and to order it:
Wouldn’t bother maxing 2nd Arthur, 2nd Isarnia, or Thorne til all of the above are already maxed (personally)
I voted Aegir because you have 3 hitters and a (best in class) healer.
Here’s why I love the frigid zombie nord:
Anyway - I understand the desire for Frida. I chose her before Aegir because I only had 1 hitter. But it looks like you can afford to make a choice between them. Frida is obviously awesome for raids, wars, titans, and D - but I wanted to write up Aegir’s pros since he’s my next blue ascension (even if I do pull Vela)
Frida good buddy. It would be good to have an ice elemental defense down in the higher end of the game.
I’ve got King Arthur who does that for me, I just like Frida for debuff & -Ice Def on 3
It’s really a hard choice and it really seems like the responses are just as varied as the voices in my head 
The only thing stopping Isarnia for me is speed.
The only thing stopping Magni for me is squishy.
The only thing stopping Frida for me is that I have Arthur.
The only 2 things stopping Aegir for me is that I have lots of tanks and I feel like a blue striker would make the most sense since I have Ariel already.
Every time I feel sure about one, the merits of the other come up.
Hmm…
Magni 793/591
Isarnia 797/655
Either would really spike my tile damage. We know either Aegir or Frida won’t help there.
If Magni fires, his +DEF helps v titans. (But then Aegir +def on all allies…plus heal)
I guess it’s a nice problem to have but I’m still stuck. Looks like the votes right now lean Frida. And, on one limb I agree, because she’s so darn versatile.
The best choice, if we consider overall damages, is Irsania. The most help will come from her, the only reason to not consider her is to have Athena.
Frida deservs to be up, of course, but she can wait imo
Whats lvl troops do you have?
Frida might be the most versatile of the bunch, but in your case I would go for Isarnia primarily because of titan damage. I use her a lot in both raids and against titans, and I do not regret ascending her.
I picked Frida.
Arthur is great but really, he only does what he does to 1 target. Frida hits 3, and dispels – and you can only get dispelling in blue with Sonya atm.
If you ascend Frida you’ll have a more helpful ice def- for raids. And Arthur can be for titans and single bosses, as his attack debuff is more helpful there
24 mana troop and 10 crit troop
So, interestingly… 4 commenters say Isarnia, 3 for Aegir, 3 for Frida, 1 for Magni
But the overwhelming vote is for Frida (25), with Aegir (12) a distant 2nd but Magni (11)a close third and Isarnia (4) a distant 4th.
Hmm.
Looking at my playstyle, I’m starting to lean in toward Magni over Isarnia, to have another heavy hitter. This would give me three fast (Alasia, Misandra, Magni) and two Average. I’d drop the 24 mana on Ariel to speed her up a little and leave Arthur on the crit troop.
I do like the -def down and tile damage for Isarnia, could likely kill 2-shot 3 heroes if all 4 offensive heroes light up. with Ariel, Isarnia could really murder if she fires twice in succession.
I feel like Aegir is edged out only because I have Ariel as a +12 on my team.
is what I’m starting to lean…
Exactly what I was going to make as a point. Magni since its gonna be easier to combine a couple of good teams of 3-2 or one Mono team.
omg, I’ve had her parked at 3-70 forever and never realized she also dispells 3 lol. Glad I read that!!
Any chance you can live with making a Super Grimm and table Isarnia? Avg speed def down to time perfectly with KA’s def down. I was on Team Aegir and voted accordingly, he’s useful in so many instances and his elemental heal is clutch.
That said, for the first year I played this game I dreamed of having a Magni so I understand your desires for giving him scopes. He’s been replaced by a lot more temptations since then, though you’ve done a nice job collecting most of them (minus Finley).
Super Grimm - not happening as Grave is getting my emblems.
Leaning hard to Magni