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I was looking at a tyranid army on the web the other day and i saw what looked like an old one eye with a venom canon?!?!Totally not legal.I put some thought into it and wondered if he took a carnifex and mutated it into a weaponbeast with crab claws.
Is it legal to use old one eyes claws if you had only 4 species in your army list?
For modelling purposes, it doesn't really matter what You have... You can model it with crabs, and simply say they count as ScyTal since they currently have no general Codex effect that would be able to be bought for the creature.
Phil Kelly's Carnifexes which were showed in the BGB (Big Grey Book, hardcover 4thEd rulebook) also had Crab Claws while having a ranged bioweapon.
ATM, simply a conversion. Though if the Crab Claws become standard bioweapons in the new Codex...
"The meat things seek to destroy ourselves. They hunt us as we hunt them but they are weak and uncertain. The inferior flesh will be entirely destroyed, all biomatter consumed. Ourselves will fight to the last, all weak flesh must be devoured."