Some advice needed. Currently I’m running Marjana,C.Rigard,C.Vivica,Magni,Kingston in raid defense.
With Magni costume out, would you choose Vivica,C.Magni or C.Vivica, Magni? other?? 
I think that prefer the C. Vivica, Magni option but regular Magni’s defense is a bit low. Now is better with c.bonus but still a bit squishy.
Would you change Marjana/ Kingston pos?
Maybe is better to uninstall the game and burn the tablet due to Telluria & Vela nerf?
Will like to hear your thoughts 
I will run C.Vivica and Magni, because Magni with C. bonus will have more defence than vanilla Magni, and standard Vivica is a meh tank.
And what do you think about swamping Kingston and Marjana position? Idea is that Kingston fires first so the attack reduction rises with the attacks of the other heroes.
Kingston must be left and marjana right
I’d run it with C. Rigard - C. Magni - C. Vivica - Marjana - Kingston.
Perhaps swap Rigard and Magni in the above.
Do you have any other emblemmed options to avoid duplicating classes?
I don’t think you need that Rigard with Vivica, and I would replace Magni with someone else if you have Kingston.
The thing is that both c. Vivica and c.Magni has defense debuff, Thais why I’m thinking in Magni,c.Vivica (Vivica debuff is all). Running Magni he should go on flank cos def buff is nearby. No luck with Magni’s costume ftm, so he’s not an option now 
About the Rigard thing, got Clarissa in last costumes event, so she could be an option to change Rigard, but will be a long training 
In blue element, my next strongest hero is Sonya+19. She is sturdy and is in defense atm, but I’m working in emblem Magni now that costume is out, so probably will be a better option in near future.
Yup! You’re right. Should be regular Magni on left flank then.
Edited with last paragraph, check and share your thoughts please, you was fast
EDIT: Confused about left/right, sorry English is not my language 
With all said before, think a good option could be c.rigard (fast with mana troop), Magni, c. Vivica, Kingston, Marjana. What do you think?
I’d place Marjana on flank, Kingston on wing, just because she’s buffier. Other than that, I think you’re good to go. Clarissa on the left wing will be great upgrade to Rigard when you finish her.
Not sure if I agree with you on that, I think both, special and classes, suggest set Kingston, Marjana, but thanks for sharing your opinion 
I suggest testing that anyway and see how your troophies react. The difference may be very subtle.