If feel that making NF castable on self, as well as on a party member, would solve everything and make it a proper ability. Because the way it is now, it's utter trash for a level 70+ ability.

If you're main tanking, it would be used as a sustain tool to help the healer. From my tests, you get about 60k healing if you manage to land 2 Fell Cleaves + 1 Inner Chaos during its window. That's more than Equilibrium when it crits, so it's quite powerful. It certainly helps your healers out in a lot of situations.

When you aren't the main tank though, the self-healing aspect on yourself becomes useless. Why bother healing yourself? Outside of specific mechanics, you will only be getting hit by AoE damage, which the rest of the party is also getting hit by. Meaning healers will be having to heal everyone by the same amount. You healing yourself won't make a difference. This makes me treat NF as a cooldown to be used on the main tank during tank busters, especially in certain situations where I can tell the healers are struggling. But that's just 10% damage reduction. 10%...

Our level 76 is not only a utility, but it is ONLY a utility during raids and dungeons. Not only that, but if everyone dies, it suddenly becomes useless. This is the main issue I have with this. A heal of 60k won't make you invincible. That's like 3-4 autoattacks from the boss. Give me a break with that bullshit argument. Plus even if you use it off of cooldown, you won't have enough beast gauge to get the same 60k heal every time, so realistically on average it's more of a 50k heal.

Bottom line is, there is absolutely no reason to keep NF from being able to be used on yourself.

As it stands now:
If you're MT, you use it on someone else to heal yourself.
If you're OT, you use it on the MT to help with mitigation.

Now imagine if you can cast it on yourself. What would change?!
If you're MT, you just use it on yourself to heal yourself.
If you're OT, you still put it on the MT to help with mitigation. What are you gonna put it on yourself for? You're probably already full HP and any extra AoE damage will be handled by healers!

There is just literally no valid arguments against this. It wouldn't change the way the ability is used. It wouldn't make Warriors invincible during fights. It would just be a wonderful QoL change that every Warrior player would appreciate.