Yup. It gives 20% extra experience, and 2x the chance of leveling the special per feeder, if you do same-color training.
Ive had really good luck getting specials to level so i never worried about that too much. And i know it gives you more experience but i usually just focused on one hero at a time. I got lucky and pulled caedmon really early so i focused on him. Then pulled grimm a couple weeks later and repeated the process. It definitely not the most efficient way but its worked for me so far. But ill probably start training properly from now on haha. Thanks everyone
Is that Kailani at the bottom left corner? She and Gunnar have spirit link, as @zephyr1 said, this skill is usefull in rare quest and challenge event when your team is underpowered.
Around next week, there will be Avalon challenge event, its hard to use Gunnar/Grimm at that event because some of the enemy reflect blue tiles/skills. You might want to level her as soon as possible if you wish to complete the epic stage.
If you don’t get 4*/5* in pulls, don’t get too disheartened. 3* is quite useful, I have 30 unique maxed 3* and it helped me in raid tournament.