Beyond fantasy
There’s no need to limit your concepts at dogmatic sword & sorcery themes; clashing elements that work unexpectedly well together are definitely good for fantasy designs, whether the approach is serious or playful. Besides the obvious cross-pollination between fantasy and sci-fi art, other types of imagery, ranging from Renaissance art to clean 3D looks can be incorporated into illustrations to varying degrees. Steampunk aesthetics are known to behave well in the mix and classical pin-up styles are a perfect way to spice up a card character.