Then it's time to make them stronger.
Valkyrie's Level Cap
Now besides the Valkyrie's ranking you will also see that they have to level up. Leveling them with battles just won't do because it'll take forever. If you go to Upgrade tab you can do leveling of Valkyries much faster there.
Here you need to drag the card which you want to level up. Now I have here a Slime Girl card. The Slime girl card has a purpose of leveling up your high ranked Valkyries faster, because it receives exp twice.
Now you can use all of those N cards you collected all this time And Maxed out the Slime Girl card.
Here's the level cap of each Valkyrie rankings.
Now you also need Arcana cards to max up the cards much faster and consume little of slime card as possible since they don't come by at all times. As explained earlier Training and Blessing Arcanas increases the experience that the card receives so We use them all of the time whenever we do an upgrade.
So how many Slime Girl Card do you need in upgrading each Valkyrie ranks?
1 Maxed out level 30 Slime Card = Maxed out level 40 SR card
Plus Blessing and Training Arcanas
2 Maxed out level 30 Slime Card = Maxed out level 60 HSR card
Pluss Blessing and Training Arcanas
1 Maxed out level 40 SR card = Maxed out level 70 UR card
Plus Blessing and Training Arcanas
Or
4 Maxed out level 30 Slime Card = Maxed out level 70 UR card
Plus Blessing and Training Arcanas
1 Maxed out level 40 SR Card = Maxed out level 80 HUR card
Plus Blessing and Training Arcanas
Or
10 Maxed out level 30 Slime Card = Maxed out level 80 HUR card
Plus Blessing and Training Arcanas
1 Maxed out level 40 SR card = Maxed out level 70 GSR card
Plus Blessing and Training Arcanas
Or
4 Maxed out level 30 Slime Card = Maxed out level 70 GSR card
Plus Blessing and Training Arcanas
1 Maxed out level 40 SR card = Maxed out level 90 GUR card
Plus Blessing and Training Arcanas
Or
15 Maxed out level 30 Slime Card = Maxed out level 90 GUR card
Plus Blessing and Training card