Hmm, I can't remember what cards you have access to during that battle. I usually played a lot with fire (only useful in long rounds though, due to the armor) and used Regiment drummer to get out more units from my deck. Plus I had some movement in my deck to boost Gascon . Also, cards that let you draw additional cards to your hand can be quite useful in Thronebreaker.
It kinda worked out for me but you can also just check out some of the newer youtube videos with the False Hope battle.
One strategy I basically adopted around that point is loading up with units that either attack the opponent (like arbalests or those Strays that move guys around on the rows and damage them) and Drummers so that at any given time I could start attacking those guys like crazy.