Yeah, I used to have her in S- but moved her down a couple of months ago…
My reasoning was: you can get a lot more out of many of the higher tier mythics. Put aside the entrance for a second… bloodbite sweeping is nice, but if you look at all the A or higher mythics they all have better sweeping power (piercing, faster, etc.). She’s also a bit slow to set that up (low speed + 70TU). The healing to keep her alive doesn’t make up for it enough. So really if she’s above B tier it’s got to come from the entrance.
The entrance I found tricky to value. In the past I loved it for PvE. Easy synergy with OoO and otherwise it’s do-able to stun/sleep enemies to pass the time. What made me change my mind is now we simply have a lot of very strong things mythics can do that we don’t need to build around something to get 4 kills. If you’re building around something it can be a proper win condition, like Excaliburdragon or Exocross. Also, leaving the enemy team with certain monsters is such a key part of the game that the entrance killing them all doesn’t feel great. So I felt like it only really had a place in UC, where most other mythics don’t do enough damage.
However, I think you make a very fair point with this. Her natural ability to stick around for the 300s is definitely a thing. I was thinking 130TU healing is too slow, but it’s probably fast enough a lot of the time. So maybe she doesn’t need much building around at all for general PvE and in super buffed content you just need a bit of support. I still think some other monsters put her to shame (e.g. Onigeist) but I’m happy to move her up one tier.