Yup, from my testings, any damage (Non-effect, so no Toxic bullets, Afterburn, Mirage's marks and etc) which will be launched before carpet use but will deal damage while on carpet will interrupt carpet.
So there's a list (Not full because it's really unlikely to hit something like this in real...
Decay no longer procs items (It was done a few weeks ago) so it supposed to work as Affliction which doesn't proc Spirit Burn. Before correcting me, please read item description for a bit
You can check this by just bying Spirit Burn + Decay and a lot of spirit items and max hero level to achive high Spirit power
I remember how you made Decay not able to proc items but it still does proc Spirit Burn. Pocket's ult with same description as Decay doesn't proc Spirit Burn, but Decay...
If you want to dodge DoTs you can buy Debuff Remover, it also heals you when you are removing DoT effect.
Counterspell saves you from 1 damage instance, so you can dodge Infernus afterburn, Pocket's ult and Vindicta's crow.
Item works correctly and it's not a bug