I have been Tanking in ESO for a long time now, but after 1.6 I noticed that I cannot keep up my magicka, then I saw the cost of Inner Fire (and its morphs) and realised that it costs more than twice as much as Puncture (and its morphs).
For clarity, here is a picture explaining my point:

And to be super transparent, here are my current stats:

So as you can see my stats for stamina and magicka are about the same (minus the regeneration part), but Inner Fire costs 2.5x more than Puncture. The reason why I have so much health is because I stack it in the build that I use.
I have no problems sustaining a proper taunt rotation with Puncture, since the stamina cost of the melee taunt is not that high and since I am stacking Blocking / Bash cost reduction jewellery glyphs. Though saying that, running after every enemy is quite ridiculous and can lead to a lot of unnecessary deaths.
However, when I try to run a taunt rotation on more than two enemies only using the ranged Inner Fire taunt it becomes impossible since the cost pretty much burns away all my available magicka and since potions are no longer as effective as they were pre 1.6 because Potion Effectiveness jewellery glyphs have been altered.
I do not think that this is a necessary "balance" to the game, but rather a very very silly decision encouraging stacking Magicka or Stamina (depending on which Inner Fire morph you have) and therefore making builds like the Health stacking one that I run much less viable.
Further, I do think ESO has the most difficult "skill-based" taunt system out of any MMO I have previously encountered, since you spend half the time managing resources like a mathematician and the rest of the time on trying to hit a target, which when corpses take Target Priority and enemies like to stack, is a very difficult task. Not to mention trying to maintain a taunt rotation, which requires a lot of experience to do perfectly.
Tanks do not need further difficulty added to this already very difficult role. So please, rebalance the cost of the Inner Fire taunt.
On a different note:
Thanks to Zenimax for making it even more difficult to now tank Veteran Dragonstar Arena on a Sorcerer or Nightblade using Heavy Armour since they ruined the self-heal build that took advantage of the Potion Effectiveness glyphs and just FYI that was already pretty damn difficult.. But I could go on about class equality in terms of tanking a lot more, which I will not do on this post.
I adore ESO, but this change makes no sense and I would love to see it reversed in some manner to make Inner Fire viable for tanking again.
"Madness is a bitter mercy, perhaps, but a mercy nonetheless."
Fire and Ice