Sealing Magic

Sealing magic
Seals (symbols, letters or runes) can be formed on any living or non living surface, when an external energy, effect, object, or magic is forced into that ‘vessel’ by the mage. The mage can also release the seal and the trapped enchantment with it. Magic power is used when a seal is created, not when it is released.

Obviously, a D rank seal will only be able to seal and manipulate a D rank object or magical technique. And so on for C, B, A, and S.