WARNING:This information has been already fixed as of Aug-Sept.
An unusual glitch(or possibly not) when a team encounters an incredibly powerful Woodland Elf in a Co-op match. The elf has over 2,000 health to begin and deals immense damage. The elf will continue to grow stronger as she levels up (often fed if your team is inexperienced), having 3,000 health by level 10. The elf can be killed, but it usually takes a considerable amount of time and many retreats. When the elf's health drops dangerously low, she will attempt to retreat, ceasing to attack and giving the players a chance to chase. A Minotaur can be extremely useful in helping to chase down a fleeing elf.
If you have faced this elf or have any comments, please post them!
I will add a screenshot as soon as I can. I saved a replay when when I first encountered her and since then I have encountered once more, proving that it was not a 1-time glitch. Both times I have lost due to newbie teammates who fed her to invincibility. --ElementalChaos