For some (e.g. Augment) companions upgrading them (Green => Blue => Epic) can increase their Active Bonus. Sometimes in order to level them up you have to do the "Companion Quality Upgrade" (costs a lot). Also, a Legendary Companion provides 15% of its ratings to its owner if summoned. I think I've heard that legendary bonus works for any summoned companion as long the legendary companion is active. All this and some more info could be found in http://neverwinter.gamepedia.com/Companion article.
well i run with an ioun stone most of the time. i don't see myself upgrading any companion to legendary any time soon due to the cost so... i guess for me the answer is no.
Comments
Also, a Legendary Companion provides 15% of its ratings to its owner if summoned.
I think I've heard that legendary bonus works for any summoned companion as long the legendary companion is active.
All this and some more info could be found in http://neverwinter.gamepedia.com/Companion article.
SoonerGM - HR Trapper
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Ethereal Justice - OP Paladin