Baumi
Adventurer
A nice trick for the Big Bad is to have Stages (as in Video-Games), where it transformes itself after been "defeated" which need a completely new Strategy to defeat. But it is important that each Stage doesn't take too long.
Example: An obvious demon-Child that hurts them psychically and has some magic tricks, but is easily defeated. When cut down, it sheds it's skin and become an huge but stupid combat Demon. After that has been destroyed the spirit doesn't die and becomes living lightning..
Also something like Lair Actions work perfectly on normal Monsters too. Upgrade otherwise mundane Monster by letting them take actions outside their normal round to become a SOLO-Monster.
Example: An obvious demon-Child that hurts them psychically and has some magic tricks, but is easily defeated. When cut down, it sheds it's skin and become an huge but stupid combat Demon. After that has been destroyed the spirit doesn't die and becomes living lightning..
Also something like Lair Actions work perfectly on normal Monsters too. Upgrade otherwise mundane Monster by letting them take actions outside their normal round to become a SOLO-Monster.