Oni are cousins to ogres, more intelligent, with innate spellcasting ability and capable of regeneration. Unlike, say, trolls, which can be prevented from regenerating by burning them with fire or acid, oni regenerate regardless of what kind of damage they take or how much, short of killing them.
Physically, oni have the typical brute ability contour of very high Strength and Constitution relative to their Dexterity, which is merely average. The fact that they excel at toe-to-toe melee fighting, however, doesn’t necessarily mean that it’s always their first choice. They also have high Intelligence and Charisma, and even their Wisdom is above-average. This means that they can plan, assess their opponents’ weaknesses accurately, use this information to select the targets of their various abilities, and employ deceit as well as raw strength in order to achieve victory. Oni also have proficiency on all of the big three saving throws—Dexerity, Constitution and Wisdom—making them highly resistant to magic, despite not having the Magic Resistance feature per se. And they can fly!
The timing of their abilities may be an issue, though, because despite their various advantages, one thing they lack is any feature that enhances their action economy. Just the opposite, in fact: Their Change Shape feature costs them an action, during which they can do nothing else. On the other hand, being able to cast invisibility at will gives them a way to avoid detection, and by extension damage, while setting up for other things. Oni’s Regeneration makes them masters of attrition fighting: the longer they can drag a battle out, the better. Their opponents have to hit hard and end the battle as fast as possible, or the oni will wear them down. (more…)