Cats (naturaly), tribbles and parrots are fine. But trolls require fire or acid which I am out of at the moment.
I just use high explosives. Which is also the reason I am not allowed to play d20 Modern anymore. Any problem the GM threw at us was solved by me with dynamite.
Lake monster? Dynamite in the water. Concussive force is much greater underwater then above.
Monster in an officer building? Fill a filing cabinet with dynamite and roll it towards the monster in a shopping cart.
Swarm of monster birds? Dynamite.
Monster wasps attracted to fire? Dynamite.
It was dirt cheap and had a lower legal restriction then most of the weapons every else in the party was using. So I was able to get two pistols, a bolt action rifle, ammo, and like 2000 pounds of dynamite for the price of everyone else's guns.