This is a very hard topic to write about as different players with different templates tackle monsters differently but i will try to see if i can make any sense of it all.
First off: this article isnt about powergaming. Its about gaining skill, making a few gps the old fashioned way, by killing stuff. if you are more interested in powergaining your skills
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IF you are a Melee char and can Survive Earthelements this comes highly recommended, even more so if you have some parry. Now there must be something better come in all these years you say, well not to my knowledge, monsters have been getting tougher and tougher and players skill levels increases, a hint to all players who melee monsters for skill is that you use a plain weapon that doesnt do much damage, the point of this is simple, the more hits you get in on something the more gains you get from that monster.
but lets make a few templates and see whats up.
If you are a mage and can somehow cast energy vortex, go to swoops they drop some nice things and a good pot of gold as well
If you are an archer above 80 or so, i suggest you go to despise and hunt ogre lords, and they dont do any magic, they last long, decent loot but dont get to close to them, cuase they hit hard.
If you are a melee char of any sorts, as i said i would recommend eartheles and when you get higher in skill and your suit is perfect then maybe you should try a demon or 2, just remember to have a bandage ready
If you by any chance is a necro, do a mix of what mage and melee chars would do, as there are many different necro templates its very hard to advice on this. some got magery some dont.
If you are a fresh tamer i suggest you go train somemore so that you will be able to control a nightmare (95 or so required)