Well a really strong build that doesn't require much gear atm is Traps. You can use a Sunblast Belt to make traps quite a lot stronger, and a Searing Touch for fire traps, but neither is necessary(and you can replace Searing Touch with a +2fire +30-40% spell dmg wand/dagger and be fine too and that shit would probably only go for 2-3chaos). I haven't actually played it but seen it played, it does ridiculous damage. Assuming no traps, Discharge build are fairly common too, however the better one requires a Searing Touch for burning and shit, see Kripp's build, kills everything on the screen instantly. In a similar but less expensive way, Explosive Arrow works too, it burns as hard as Discharge but from range, only takes a bit longer to setup, and the only item you need for it is a Quill Rain, which a 4L of isn't worth much, like 3chaos or so, probably less on domination/old servers. Then you have the good ole Freezing Pulse, need to tank up hard and freeze shit, 15+% FP is recommended so that's some expenses but rest is cheap shit. Similarily, good ole EK build, basically most of the usual caster builds.