I'm talking about self buff/transformations spells. They have long since a staple of the fantasy genre, a bit underused perhaps, but they usually show up even in kid stories, such as old Disney animations. But for some reason they rarely show up in manga, they usually only use Summoning magic and Evocation, of which they usually use Evocation badly, either having the Mage only use magic that belongs to an element or restrict it's power a lot.
Here is one rare story in which the MC does use transmutation spells. Another would be Goblin Slayer I supose, with the Lizardman Shaman using spells to increase his physical strength just like here.
