Ruin Explorer
Legend
None levels. Ain't nobody got time for that.
Just give the monster the abilities you want it to have. Bump up hit points, saves, AC, damage, etc, etc.
It's dangerous to go alone, take this!
Seriously though, Giffyglyphs's stuff is amazing. I love Darker Dungeons but his Monster Maker is probably more universally useful. It has changed the way I customize monster. I recently ran a boss fight for a solo hag against a part of 4. It was epic.
Oooooh nice. I shall provide that link to the DMs I play with also.