When I don't know what to do than I go with Abby, Mash and summer Abby.

Morgan merlin castoria

Well, I don't think I have anything to say. Empty0414 - already told you everything you should know. Just Morgan + Merlin + Castoria. That's is.

The only enemies this team cannot beat are ones with buff removal

Not impossible but it will definitely be a ton harder

Van gogh and castoria

I don't believe with "universal team" that can beat anything. You Always have to adjust your strategy against different enemy to make sure you can win. But, since you ask, this is some servants I use in a CQ.

I have created two teams for this type of scenarios first is Sitonai, Castoria and Raines

2nd team is monkey go boom consist of Arjuna(Alter), Merlin, Oberon,Koyanskya & Reines Usually for Blind fight I go with 2nd team, If things do seem difficult I go with 1st team .