I use the rifle. At the start of the elf archer levels, I jet pack up to them (zig zagging in case they are targetting me), and smash them in melee. When they respawn, I just use the rifle. The central tree trunk isn't "real", so you can shoot right through it. That means you don't lose your position, allowing you to do whatever you want from the archer's perches.

I don't like the red aura because you are vulnerable to any attack while using it. The elves on the ground can attack you in the archers perchers if they stand in the right places. With the rifle, I blast those elves below away while blasting the elf archers respawning.