Rhea gains much of her magicks from the magical leylines that naturally run throughout earth. Much of her power also comes from naturally occurring energies from nature itself. The ability to use strong magick effectively, doin rituals, and enchantments all comes down to how close or how far away she is from a proper aether leyline.
For instance, the further away she is, the more of her own energies she has to use in order to draw out magick. Which means if she doesn't rely on the earths energy, she'll have to use reserve power from within that'll tire her out.
Her reserve inner magick is extensive, especially when it comes down to combat magicks. So when in combat, she'll use more "trick" magicks, or "quickening" spells. Which mean more simplistic magicks to get a job done as efficiently or with minimal destruction as possible (since she strongly doesn't like using death as a last resort).
More often than not, Rhea would rather afford herself the luxury of not having to fight. Instead using wit and conversation to get out of situation. She would much rather enchant items, make potions, or otherwise go hunting for magical artifacts rather than battle.
She was trained in many of the magical arts. Many would say she's a jack of "most" trades, and a master of none.
Her dream is to someday own her own magical shop and sell off her gems, items, and potions to those who need them.
In the meantime, finding artifacts helps make her money to further her dream. She does tend to sell the items, but keeps any potentially dangerous items off the market.