[Mambus]

Each valkyrie wants different sort of items, right click the item and choose donate.

The interface is a little buggy since it looks like nothing happened, just left click on some other item and you should be fine. Save before donating since sometimes the game crashes.

You can get each valkyrie up to level 4 by giving items (check the level and bonus by holding a cursor on valkyrie portrait). For every level, passive bonus of the valkyrie gets better e.g. +% gold found for the first one. The active ability gets better as well.

To get valkyrie to level 5, you need to finish her personal quest. You get the quest by talking to her, when she reaches level 4.

The best strategy I found is to donate them items level 1 - 3 since you only lose crystals by giving those items. Save items level 4-5 for deconstruction (artefactor skill needed) since you can get skill runes from them. To reach level 4 from level 1, you need to give about 6-7 items.