Defiler Cuisses
Bone Spirit’s damage is increased by 400% to 500% for every second it is active and will also freeze immobilize enemies on impact.
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This way Defiler Cuisses is Thorns friendly.
Of course immobilize has to work on bosses.
In addition, Freezing is not needed since ennemies will focus on minions and minions no longer take damage. They can tank efficiently and restitute Thorns damage.