Well, the projectiles currently don't account for angle; they just use the player's pitch.With Scream in particular, I found that it only traveled in a circular formation around me that didnt account for height, or angle. The first time I tried it was on the stairs at E1M2. Either the Imps outlasted the power, or the attack didnt really work
In any case, the current setup causes some problems, like if you were to aim up some stairs (like the stairs in E1M2, possibly) it wouldn't hit enemies behind you; those projectiles would aim up as well. So I'm reworking the function so that the pitch of projectiles behind the player are inverted, so that they travel down the stairs instead of up. Note this will only affect the rear projectiles. The front projectiles you'll be able to aim up.
Also, I reworked the damage formula so that the gradual damage from the Scream projectiles multiplies with each projectile that strikes an enemy. These changes will be in the nest release.