If it only hits once, then what does "Beam lasts for half a second" mean, then? Does that just mean it fades with no effect?
That would give it an average of 666 Base DPS, which is very strong (Stake Launcher only has 500), but also considering that it takes 3 seconds to charge, it might still kill crowds a bit slower than its competition. You only get one shot per 3 seconds, and if any of them somehow survive the blast, they're going to survive another 3 seconds, whereas something with a bit less DPS but faster firerate (say, Stake Launcher) may have killed that thing within those additional 3 seconds, leading to a faster death. That said, I would be surprised if anything short of a boss survived a hit of 2000
base damage.
Another consideration is that if more enemies spawn during the charge time, they'll have a few uninterrupted seconds to approach you or fire upon you, which could be dangerous. You
could charge it up while you approach a line of targets (such as falling down towards the trash mobs on the ground after fighting a Pumpking) and blast all of them away before switching to a
different weapon for any new spawns or surviving enemies; I actually quite like that usecase, now that I think about it. I assume you can hold the charge for as long as you like before firing? If you can't, it would likely feel quite clumsy and unreliable to use effectively.