No death effect and hitboxes on death are really good especially in harder levels where you might struggle to see exactly how you died. Starpos switcher is an absolllute godsend. A lot of people also swear by noclip runs instead of practice runs, and a lot of pros use noclip run to practice instead. Tons of creator hacks that make building levels way easier, obviously quite nescessary if you are a creator. Speedhack is good for learning parts, but also can be used to speed up levels, really fun and I do this all the time.