Upkeep base is in Stamina and values vary with fatigue%.
The hits can be critical hits.
Each hit drains 10 stamina.
This ability immobilizes the user and disables all abilities for its duration. To exit the mode before the end of combat, you must deactivate the mode manually. This and the limited range of Two-Handed weapons in general makes this talent very situational.
Per discussion, this mode renders the character immune to Childers' overwhelm, a highly damaging ability with very powerful control mechanism that completes ignores resistance (when cast on valid targets). In extrapolation, the ability would also be an excellent preemptive anti-CC tool.