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Depends on what you're going to do with it. If you're just going to be training combat in general, then the rapier is perfect. It's accurate and can speed up slayer tasks so much. It's especialy noticeable during dragon tasks where the stab option comes in really handy.
If you're going to be doing alot of boss hunting such as tormented demons or Bandos then I've heard that the cls can be really useful there. Some teams also have requirements for a chaotic such as cls, so that could be useful.
Finally I think the maul is mostly used of PKing or PvP in general because of its high hits, so really it depends on what you like doing most on RS.
Personally, I'd recommend the rapier as your first chaotic. It can be used for most melee combat situations whether it be training or bossing so I reckon it's more useful than the others. You'll be able to get tokens faster at higher dg levels anyway when you can buy the rest of the chaotics, but for the time being I think the rapier will serve you well.
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If you're going to be doing alot of boss hunting such as tormented demons or Bandos then I've heard that the cls can be really useful there. Some teams also have requirements for a chaotic such as cls, so that could be useful.
Finally I think the maul is mostly used of PKing or PvP in general because of its high hits, so really it depends on what you like doing most on RS.
Personally, I'd recommend the rapier as your first chaotic. It can be used for most melee combat situations whether it be training or bossing so I reckon it's more useful than the others. You'll be able to get tokens faster at higher dg levels anyway when you can buy the rest of the chaotics, but for the time being I think the rapier will serve you well.