Rule 107.16 · Numbers and Symbols
The text box of a Class card contains class level bars, each of which is a keyword ability that represents both an activated ability and a static ability. A class level bar includes the activation cost of its activated ability and a level number. Any abilities printed within the same text box section as the class level bar are part of its static ability. See rule 716, “Class Cards.”
Subrules
“[Cost]: Level N — [Abilities]” means “[Cost]: This Class’s level becomes N. Activate only if this Class is level N-1 and only as a sorcery” and “As long as this Class is level N or greater, it has [abilities].”