I realise that there are old threads on this, but I wanted to give my thoughts on frost staff tanking as well, having levelled a frost staff warden tank. I've done all normal dungeons and a fair few veteran dungeons with great success, but no trials. Keep in mind that I am purely speaking from a PvE point of view.
Putting it into a bit of context, this is the build I've been working towards and with, having success in veteran dungeons:
esoacademy.com/builds/magicka-warden-frost-staff-tank/
First, and very importantly, I just want to say that I hope you decide to keep frost staff for tanking, because
it is a very different way of tanking that is very fun! I've been having a blast with it and if the quirks are worked out, it could even be viable.
A lot of the issues that I've experienced have already been highlighted across different threads on the forum and they are:
- Taunting with the frost staff is too slow. I really like it being an option and it's useful in many cases, but if you have to tank several bosses it really eats away at your block time. I imagine it being fatal in trials. It could be solved by putting the taunt on bashing and turning that into magicka cost as well, putting it on destructive touch or making heavy attacks with frost staves faster, while lowering damage (which might also make some of the heavy attack enhancing sets viable).
- You lose a piece of equipment, making it impossible to get a 5, 5, 2 armour set setup. Ontop of that you also lose armour and a piece of equipment that has a large enchantment for 900ish health.
Those are the two primary issues that I've experienced and especially for trials I imagine they are deal breakers compared to the sword+shield. You lose quite a bit by choosing a frost staff over a shield. In order to accept that you lose the 12th piece of equipment and its bonuses, you'd expect the frost staff to compensate with something else that makes tanking viable in some other way, but it currently doesn't.
What it does offer, in my experience, is the following:
- It encourages ranged tanking without any heavy magicka / stamina cost from inner fire (and morphs). It can be very useful to grab aggro from a distance.
- A free ranged taunt, albeit a slow one.
- Using heavy attacks so much offers great resource management.
- Using heavy attacks so much offers opportunities to proc effects caused by heavy attacks. Like the Lotus Blossom heal and it offers opportunities to use heavy attack enhancing armour sets.
- A small damage shield from heavy attacks. This is nice enough and seems to have been an attempt to compensate for not being able to block all the time, but it really doesn't feel like that significant a reward.
- Magicka cost on blocking. I love this and this makes pure magicka tanks possible.
To me, ESO is all about different possibilities and choices. Frost staff has finally offered another way of tanking and I've had a lot of fun with it. I really want to see it kept for tanking and for it to improve and become as viable, in its own way, as sword / shield. I like how different it is to tank with and I'd love to see it compensate for the loss of a shield in a way that it doesn't just feel like a two-handed sword/shield, but as something else. I don't have the answer, but I'm sure it's out there!