In the Lapis game I have been the "B" nation, I guess
If I had just figured out a bit earlier Baalz' Agartha is not allied with Kuritza's apes, and I would have pulled the troops back from the southern campaign way earlier (and could have saved some of my own SC's, which Kuritza took out with great efficiency). However, the C'tis Miasma dom has been really nice defence against the blitz of Agartha, as Baalz has been very reluctant to bring in troops to siege the forts.
So, as far as I can see the counter to the drop doctrine is to ensure you have something to kill large armies, and some way to survive the sieges, until you can send out the hunting parties to grab the blitzers. In the case of MA C'tis the dominion itself is enough, but mages with access to some weapons of mass-destruction will do fine; just be sure you don't fit on stuff that is too expensive, and send them on a kamikaze with the purpose to kill as much as possible before they croak; say Wrathfull skies and Blink, or Earthquake, or Wind of Death, or Creeping Doom + Foul Vapours, etc. The point is to have most of the opposing blitzers tied down around your forts where they will accomplish nothing (except preventing your freedom of movement, which is important too), instead of their armies sieging (and taking) your forts. You need time to get send out spesific SC hunter teams (and hope your diplomacy will save you with others attacking the blitzing nation too).
It becomes actually a sort of Vietnam war, with small scale engagement going on everywhere, while each side is quite reluctant to throw in the big armies (as losing a big army might well mean the end).