Cards Menu | Power Up Option

When I go into the Cards menu, at the bottom there are three options. Two of them, Equip Hero and Fortify Card are crystal clear. The third option, Power Up, is not. What exactly does this option do? I have had some Bounty Quests where I've had to Power Up my Heroes a set number of times. However, I have no idea what this does to my Heroes, and the Wiki doesn't cover it either. Please explain. Thanks.

Power up is for giving your hero's a little tiny boost to their stats using Hero Stones. (You know the blue diamond things in your warehouse?) The more stars your hero has and the higher the tier, the more it takes to power them up. Just remember it's a extremely small boost, like +1 to +5 each stat for the power up x10.
Hope this helps.

It might be a small boost but it adds up quickly, my talia is barely powered up and I get an extra 5.3k hp, 1.4k attack, 500 defense and 1000 crit. I'm hoping that when I tier her to master talia it will go down a little bit since it currently costs 5 every single power up.

Thanks for the prompt and educational answers.

You're welcome, that's what the forums are all about!

The amount of Hero stones required for a Power Up is based on your tier. You get more bang for your buck if you dump a large amount into your heros before evolving them