Helm of Fear is really meant more for very controlling Warlock builds, where you can see it pay off over a longer period of time. It essentially functions as an infinite defense, but is arguably better in that context since it is one of only two spells (the other being Forcefield) that can stop Unavoidable attacks, which can be a nightmare for control builds.
Of course, the additional benefit is that you can also have Deflection Bracers AND the Helm equipped for a pretty solid chance to avoid an attack no matter the situation, since one activates in the declare attack step while the other activates during the avoid attack step. As it's an equipment, you can still lean on the Battleforge as your main mana/action advantage conjuration.
That said, it's not something you just throw out there like the Whip and expect it to be good. You should use it mostly against more mid-late game Beastmaster and Warlord builds, which can gain a massive action advantage via hordes (which you're going to inevitably face since, as a very controlling Warlock, you've conceded your early game).
