Let's just turn it into a general anti-Sedna thread. 
Should I be embarrassed if, as the Unclean Beast, I find I must cede the battlefield to Sedna every time, from the beginning, if it's a 1v1 situation?
When I see Sedna, I fight her once to see if she's being run by someone who knows what they're doing, then if she is, from then on I simply run to fight somewhere else on the map. I just can't figure out how to make Sedna run away from me.
I read that one should take out her monks first if she has them. But I find that the time it takes to take out the monks leaves me unable to take her out, or scare her away, or anything. I just have to run. And she resummons, and she's golden. I mean, I guess it cost her some mana, but I assume she's got good mana items and armor, so that's no big deal.
Past the first few levels, she can even fight me if I'm next to a tower.
I usually do spit/ooze Unclean Beast, focussing on HP items. I use Blood of the Fallen, though I've been experimenting wiht Marda's Hammer. (Blood seems much better in the long run.) Spit might not be the best thing to do against Sedna since she's got a fairly early (level 7) ability to cancel negative effects. Maybe ooze and (stats and/or bestial wrath) would be better? Bestial wrath is never enough to kill, but maybe it'd be enough to make her run away and let me do the farming.
It's the healing. I can't get past the healing. And in beginning levels, I can't interrupt it. (I'm not sure I'd be able to interrupt it later with foul grasp either--don't they have the same cast time?)
In my experience, from sometime in midgame onwards, she can even handle 2v1 against her pretty handily. Is this normal, or am I probably just doing something horribly wrong?