DoT's should work like bleed - single hit makes an enemy take damage over time without the link needed. Otherwise it's not damage over time , but more like Damage when Linked. That way an DoT Missile spell would deal direct damage AND damage overtime without linking, so you could cast the next DoT spell whioch Would (or wouldnt) stack against the previous DoT (afaik Bleed stacks - so should DoT's).
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