The name would be Dark Shadow Wolf. ( It's also a canon move he used in the manga )
Basically he would transform into a large shadow wolf, which increases his overall movement speed and damage at the cost of a lower defense ( takes more damage and lower blocking strength ). Additionally, using this move resets all of his skill's cooldowns.
This move has a 30 second duration and it's cooldown would be 50-70 seconds ( up to devs to decide ).
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