As title states, I want to know if she has a counter at all. Played a 2hr (I shit you not) 1v1 on Crucible with UB vs. Sedna and I can't think of any DG that could actually defeat her in 1v1. At first I thought "Alright, so Sedna is counter to UB. That's fair enough" but then I started racking my brain trying to think of any other DG that could actually defeat her in 1v1.
We were matched level for level. I upgraded my citadel more quickly after finding out I couldn't even get her below 50% health (just ran around killing creeps). It was 0/0 Kills/Deaths for both of us so neither got fed XP or items.
I seriously want to hear peoples' experiences with her and exactly how they manage her in a more in-depth manner than "gang bang her".
That's probably because you're using UB. Sedna can nullify venom spit and heal herself when she's in trouble. She'll also silence you to avoid interruptions while healing herself. When I use QoT though, sedna almost always runs away first because QoT is an excellent mob sweeper. In other words, sedna loses her minions and ends up losing mana for healing herself and resummoning her minions. QoT, on the other hand, will decimate her minions with ground spikes. If sedna has her heal, QoT has her bramble shield + mulch shamblers. She can silence QoT, but that's not enough to drain her HP + bramble shield.
The food web is actually quite funny. As QoT, spotting UB stalking me is equals to teleport. If he's already too close, I'll bait him to interrupt me with spike wave. If he does interrupt spike wave, I'll teleport. If he doesn't, I'll just use wand of speed to out run him and mulch shamblers on the way home. The problem with QoT vs UB is that your bramble shield is not very effective against foul grasp. On the other hand, QoT vs sedna is equals to sedna losing her minions and mana although sedna vs UB equals a frustrated UB. UB is also my assassin demigod and when I'm fighting against sedna I take out her minions first. Sedna on her own isn't a threat. I also use venom spit on structures and on sedna while her heal does not nullify it yet. My priority against sedna in 1v1 is to take out her structures even if it's slaughter. This way, I'll be able to chase her down without worrying about the towers. Although, she's still a pain in the arse if the player is good at cowering.