Would really really like to have two tools in the pgcc:
Combat Dummy: it has infinite health and just exists to be hit over a period of time. Much easier to determine damage ranges, bugs, and mechanics without the combat log being cluttered with enemies attacking and so on.
It might also be cool if it could somehow print out a breakdown of the incoming attack!
Example: You did 19 piercing, 4 slashing, 2 bludgeoning, 9 divine. Your attack bonus was 52.
Your max damage was 90. Your minimum damage was 20.
Etc.
Thats probably really complicated to do but I'd settle just for an infinite hp dummy. The ones in the backroom have weird immunity and resistance breakdowns that I found made them more difficult to read then they ought to be.
Auto 5% Basin: automatically hard 5% enchants anything. This would help figure out gearing, and runes, without having to spam tons of items in the basin over and over.