D&D 5E [5e] Need help with a 20th level wizard

[CTurbo]

Dang Paladins always ruining everything! Lol

 

[FieserMoep]

He has a mansion and is a bbeg, where is the private army of mercs? A ton of competent physical attacks works wonders. Have Some archers in heavy cover and hidden areas around the mansion. The wizard is supposed to be smart and a mage killer party is visiting him. Make his mansion a mundane trap house with an army inside. He adds spells where necessary and may mostly utilise just brutal utility stuff like wall of force etc.