I've been collecting the new deck until I ran into some banker (?) with Nilfgaard deck that keeps playing 4 spy cards. I can't seem to beat him no matter what deck I use.

Anyone has any advice?

Use Decoys to take his spies and use them for yourself, and your own spies. Try to have medics too, to use the spies again in the next turn.

The closest I came to winning was when I got 2 Decoys, but he still has 2 extra spies, so I still lost. I'll probable just wait until someone updates the CT table to 1.21.

Playing one of the innkeepers, and she had 2 Dandelions and 2 Villentretenmerths all in the same round. Cheating much.

It's easily possible to have 3 spies and 2 medics with the Northern or Nilfgaard decks:

NORTHERN
----------------
*Avallac'h
*Thaler
*Dijkstra
*Stennis

+Yennefer
+Dun Banner Medic

NILFGAARD
----------------
*Avallac'h
*Rideaux
*Skelen
*Fitz-Oesterlen

+Yennefer
+Etolian Auxiliary Archers 1
+Etolian Auxiliary Archers 2
+Siege Technician

Scoia'tael have 3 medics (plus Yennefer) but only have Avallac'h available as spy.