Moonboost
"Moonboost" or "moon boost" is an umbrella term for tech that utilizes the movement of a moon block, almost always the movement caused specifically by Madeline dashing into the side of one. In RTA contexts, the term usually refers to a moonboosted demohyper. In TAS contexts, it usually refers to dashing into the side of a moon block, then multiboosting from it as it recoils from the dash.
Note
The adjective "moonboosted" can describe any tech whose resulting speed has been increased by liftboost from a moon block. However, since it's usually quite complicated to gain liftboost this way while performing other tech, it's often easier to just fully explain what's going on in such a situation.
A moonboosted super or demohyper is performed by dashing horizontally into the side of a moon block and getting cornercorrected on top of it, which requires the bottom pixel of Madeline's hitbox (red) to be at or above the 4th pixel from the top of the moon block. Doing this causes the block to recoil and thus gives Madeline liftboost in the direction of her dash while she's on top of the block.
If a moon block starts a recoil before a previous recoil finishes, the block will instantly snap back to where it would have been on that frame if it hadn't been recoiling. There are two ways to cause this to occur:
There is no cooldown for triggering recoils by hitting a side spring attached to a moon block. Hitting the spring while the moon block is at least 8 pixels back (10 or 11 frames after a recoil starts) will cause the block to push Madeline when it snaps back, giving her 250 X liftboost. Madeline can then walljump on the next frame to leave the block with 380 X speed rather than the normal 240 from the spring.
Also known as a recoil moonboost despite my best efforts. There is a cooldown for triggering recoils by dashing into a moon block, but that cooldown ends before the recoil actually finishes, so triggering a second recoil early will still cause a small snap. The extra liftboost from this snap is only given on the frame the snap occurs, and the second recoil behaves as normal.
For horizontal liftboost, the most effective snap is achieved by triggering a recoil by dashing away from the desired direction, then triggering another recoil towards the desired direction as soon as possible. This yields an X liftboost of approximately 80 -- the exact amount depends on how far the block's X position is from the origin.
For vertical liftboost, the most effective snap is achieved by triggering a recoil by dashing downwards, then triggering a horizontal recoil as soon as possible. This should theoretically yield a Y liftboost of up to -40 or so, but in practice the amount can be much lower due to the block moving down when Madeline brushes the top of it.
Celeste TAS