For that one power, yeah. Anything else, I have to do a spell for, so I'd only be as powerful as someone else using a spell for it. Though, spellcasters can get pretty strong. It really depends on how developed the powers are. If someone's been practicing a lot longer than me, then they could probably do a spell that's stronger than my power, but they'll stop getting stronger at doing it at a weaker... level, I guess, than I would.