Brain Scrambler

Scutlix Gunner drops it during Martian Madness, meaning the rider rather than the creature it is riding. The event is post-Golem, so this arrives late, and the drop is not generous, though it was made considerably more common than it used to be. A full event usually throws enough gunners at you to make it a reasonable target.

It accelerates hard, tops out faster than most things that can chase you on the ground, and jumps high enough to clear terrain you would normally need hooks for. Fall damage is cancelled outright, so the height costs you nothing coming back down. It cannot fly and it has no double jump, which is the honest limitation, but the jump alone covers most short vertical problems.

The eyes fire red lasers on their own at anything in front of you, several times a second, at very long range. That damage is fixed and untouchable: no armor set, no accessory, no critical hit and no knockback. It is a floor and a ceiling in one, which means the mount contributes nothing to a late build's burst but still adds free damage forever. The blind spot is behind you. It only sees a cone ahead, so a target at your back gets ignored until you turn around, and attacking in that direction turns you. At smaller resolutions the detection range extends past the edge of your screen, so it will happily shoot things you cannot see.

Touching water or lava does not dismount you the way some mounts do. With Lava Waders or similar it walks across the surface instead of dropping in. The lasers are unaffected by liquid as well. Pair it with Neptune's Shell or an upgrade and the whole package keeps working underwater, which frees the accessory slot a movement item would otherwise occupy.

The Solar Pillar is the standout. You can cross the arena faster than the enemies converge, and the lasers chip away at the shield count while you do. The warning that comes with that: Selenians reflect projectiles, and your mount's lasers count. Ride into one and you get shot by your own eyes, which escalates fast.