I started playing RPGs about ten years ago with the 3rd edition D&D starter box. I found a few interested friends and we played regularly until we graduated high school. I was almost always the DM--my first experience as a player wasn't until several years later!
I've always had a few house rules in my games, but I think it was the transition from 3.0 to 3.5 and later to Pathfinder that really spurred my interest in the design of the game itself. I can't help tinkering with rulesets, whether it's Pathfinder, tabletop wargames, or computer games. To share my work, I've just started a design blog at http://vilgames.blogspot.com.
Have you designed a lot of monsters before?
No, mostly just minor tweaking of monsters as a GM. I've thrown together a few things for use in home games, so I was familiar with the monster creation rules, but certainly nothing before now that I would have shared with the public.
Why did you choose the warpstar and what thinking went into your design?
When I was first reading the Bestiary wishlist thread, I noticed a lot of requests for a time elemental, which started the gears moving on what became the temporal distortion ability. In my home game, one of the schools of magic is warp, dealing with manipulation of time, space, and other basic laws of reality; so the request for "monsters based on light, sound, gravity, and time" immediately caught my eye and my imagination.
The warpstar started out conceptually as a sort of miniature traveling black hole. I wasn't expecting to make an ooze, but when I went to determine the type, it made a lot of sense; it had all the right immunities, it was mindless, and there was precedent for flying oozes in the plasma ooze.
The hardest part of designing the warpstar was definitely the special abilities. The general concept of the distortion aura, gravity well, and temporal anomaly abilities came to me early in the process, but pinning down an appropriate power level took multiple test combats. One of the tests wound up with three of four characters engulfed and rapidly disintegrating while the fourth desperately tried to finish off the warpstar! Needless to say I reduced the DCs of the engulf and distortion aura abilities after that.
In your opinion, what makes a good monster?
For me, the best monsters meet two criteria. First, they have some distinguishing feature, whether it be a special ability, unique appearance, or unusual behavior, which makes them memorable to players. This is doubly true when designing for an established system like Pathfinder where the design space for "plain monster" is already filled. Second, ease of use for the GM is important, and this can often come into conflict with the first criteria for monsters with many spells or abilities. This was a major consideration while I was designing the warpstar, particularly with respect to the warp reality ability.
What are your favorite monsters in the Pathfinder RPG (including monsters in 3rd-party products), and why?
I think I would have to go with the troll and the tarn linnorm. Trolls are a great example of a simple monster that can still be memorable and force players to alter their tactics. The tarn linnorm, terrifying destructive potential aside, has a few details that make it stand out to me, like its regeneration that can only be overcome by cold iron and its unique death curse.