The Stilva is a demon enemy from Final Fantasy IX. It is not a particularly difficult enemy to defeat compared to the other monsters in Memoria, but it can still deal decent damage.
The best way to confront this foe is to come equipped with Fire resistance or absorption, as it will absorb both its Firaga and Red Clipper attacks. It can then be dealt with in any manner, as it has barely any status resistances. To make it even easier to defeat, casting Mini severely hampers its physical abilities.