I played the warlock and made a few key mistakes in the game.

Early on, the Forcemaster got in my face and I started reacting to him instead of doing my own thing.  It was a matter of panic, and it took me a few rounds to regain my composure.  Classic mistake, and it put me behind the mana/gear curve.

In mid-game, I laid two fireballs on the FM in one turn not realizing he was wearing a dragon scale hauberk and that fireball was avoidable.  He was near death and bogged down with curses at the time.  The turn before I had exploded a ring of his (arbitrary choice) and if I had been paying attention I would have exploded the hauberk instead.  Again, it was a matter of absent-mindedness and not knowing the cards well enough.

Still, I have gotten somewhat scared of FM as a warlock player, and the amount of pain I poured on webcatcher this game  has given me some more confidence.