Tenacity up should mirror Potency up

1) As it currently is, Tenacity Up is not an appropriate title for this ability. It provides so much Tenacity that you can not in good conscience call it an Up. It's virtually Unlimited Tenacity at this point.
2) You cannot even call it Debuff Immunity either, because it not only resists all Debuffs that can be resisted, it can also resist TMR and very soon, it can also resist Cooldown Increase (DT & DN).
3) Tenacity Down is mathematically the opposite of Tenacity Up, but subject to the minimum irreducible 15% Base Resist Chance, which effectively makes it NOT as good as Tenacity Up. If you design Tenacity Up to always resist debuffs, TMR and so on, then you should at least make Tenacity Down equal by always getting debuffed, TMR and so on.
4) You have multiple arena viable characters which give Tenacity Up to the entire team, but only 1 character who has a chance of AOE Tenacity Down(Dengar which you can judge for yourself if it is viable in Squad Arena anyway).

Last but not least, I have low expectations that anything will be done to remedy this imbalance. But enough whining seems to have brought at least some Dev attention to mechanics and in some cases, even changes to mechanics whether it's a nerf or bug fix or what you want to call it. I'm not calling for a nerf here, but I want it balanced, i.e. Make Tenacity Down functionally the real opposite of Tenacity Up, design more arena viable characters that can inflict AOE Tenacity Down.