I prefer functional variability over duplicates so I would max your Arthur to give you another elemental defense debuff and sniper next. With the current meta my next choice would be Vela.
Edit: Moved your topic to the category where it will receive correct feedback.
You can’t go wrong with either Vela or Alasie. I have found the punch of a fast sniper to be the most valuable in the game. Magni is too glassy without a costume. Considering that you already have a Vela leveled, I’d go with Alasie.
I would also go with Arthur, In case you do Not feel comfortable to ascend him, then Alasie dupe… she is still one of the Top snipers and may always find use in war attack teams…
Velas secondary effect won’t stack if you take two. 2 Alasies will debuff all enemy heroes with the mana slow. Frida dupe could be good against red tanks, which seem to be gone forever.
Why not Misandra? She may help against the mana problems, when that last tile is desperately needed but any move on the map would cause charging cascade. I regret that current meta kind of forced me into maxing Vela, I really hoped I would do Misandra first.
misandra, she can be great if she hits multiple times, but if not it is really weak and a wasted spot. i used her at 3.70 for some time with krill or ariel and valerias in a later mono blue war attack team with mediocre success. in meantime, she is covered with dust. but acknowledged, there are split votes on her.