You can kill them using any weapons they are pretty weak, but they don't have a weakness like pyre's.
Waterfiends
Any weapon that has a great crush bonus:BattleaxesMacesMaulsWarhammers
minotours for right skull half,
The best monster to kill in Runescape would be the King Black Dragon.
depends if you have good armor, weapon and food you should kill moss or hill giants
stronghold of secutity i like
look at link
The best place to kill zombies is at the armor zombie place. IT is where everyone get 99 str.
Use a great sword
the best way to kill him is by having the R.Y.N.O
At your level, I would say killing Experiments ( Level 25 - 100Hp = 400exp per kill ) near Canfis.
Best way is to player kill "pk"