Using certain actives and spells when untargetable

Correct me if im wrong but we cant activate actives or spells when untargetable. (Tell me if we can cuz i want to know) Using active that heal or shield such as Botrk, Mikael's Crucible and Locket of the Iron Solari. Or actives that damage like Deathfire Grasp, Bilgewater Cutlass, and Hextech Gunblade. And spells like clarity, heal, barrier, ignite, and cleanse.