Guaranteed direct crit and infinite beast gauge, while a nice thematic touch, don't really make a compelling or complex ability. I propose to change inner release to something more in line with level 50 warrior's burst where you ideally wish to use 2 inner beasts and 1 storm's eye or path under it without overcapping.

To maintain this level amount of gauge engagement, I think the removing the unlimited beast gauge skills aspect from IR would be a good step. This would require the use of infuriate and 5 CGDs (HS > Infuriate (50) > Maim (10) >> SE (10) >> HS >> Maim (10)) before the opener to be in a good position with 80 gauge to start the burst.

As Fell Cleave, Inner Chaos and Inner Beast cost 50 gauge, this would only allow for Inner Chaos and a single Fell Cleave, so perhaps Inner Release should offer some kind of discount on gauge skills - 50% say - or buff to gauge generation for the duration/stacks. Assuming the discount option is chose, the burst would start with Inner Chaos and use at least one Fell Cleave to allow another Infuriate, followed up by emptying the gauge and then primal rend (4 Fell Cleaves, 2 Inner Chaoses and a Primal Rend). To allow for easier weaving, it could be beneficial to replace the gap-closing element of Primal Rend with a Damage over Time effect, something every other tank has at least one of (Sonic Break/Circle of Scorn/Living Shadow/Song of Torment).

The tooltip could ultimately look something like
Inner Release Duration 18s
For duration halves cost of Beast Gauge attacks.
Additional effect: increases damage dealt by 30%
Additional effect: grants Inner Strength granting immunity to all the statuses except the ones that are going to hit through regardless or the ones it doesn't.

This change would also have the added effect of quelling complaints about forced direct crits, which are effectively the same as being unable to crit. A potency adjustment may be in order to address this, but it might be fine.