https://imgur.com/Lx9RA71 (charge spell)
https://imgur.com/bdNnuD1 (helmet loop spell)
https://imgur.com/0P41584 (helmet second slot, feel free to remove the particle trail)
https://imgur.com/QP29ky9 (CAD primer spell)
https://imgur.com/IjTOrSv (Helper spell, optional. Reads stats in chat and fires charges on crouch.)
Usage:
With all spells equipped as intended (helmet slot 1-2 and 2-3 using loop and fire respectively), select the helmet loop spell and detonate to start the loop. Then, place as many charges as you like (preferably using leggings). Select a target with the CAD primer (shift right click restarts the helmet loop, in case you ran out of psi which stops it). When you have done so, a debug in chat will continuously show the selected entity. The arrow will only target that entity, so ensure it's correct.
Finally, shoot an arrow.
The arrow will check each tick if it has line of sight on the target and, when it does, will trigger all charges causing it to fire directly at the target.
Notes:
Grass blocks LoS, causing the spell not to arm and accelerate the arrow
The ability of the arrow to turn is dictated by how many charges there are. The further the arrow is from alignment with the target, and the longer the range, the more charges are needed for it to be accurate.
Mob projectiles can trigger the spell. For best results, clean up nearby stationary arrows (the spell will ignore them, but it won't cast so long as they're the closest projectile)
The spell uses saved vector 8 to track its target. If you need that, change it on each of the spells.
A bit long, so here's a quick video on how to set it up and use it https://medal.tv/games/minecraft/clips/l72Rw7B17y1oCcrHs?invite=cr-MSwwVU8sNzAyMTY2MzI&v=33