Are there any improvements that can be made to this game UI?

So I made another game (I will make something useful one of these days) and have been told there are some problems with the UI. I fixed these, and decided to put a question about it here.

When you first open the game, it should look something like this:

That is the starting screen. To begin your turn, select a card by clicking a card name on the left hand side but closest to the "Turn: Angels". When you do so, the name should become a bit brighter. This means that the card is selected. You can now attack the enemy card by clicking on their name.

Cards can only attack once per turn. Cards can only attack if you have more mana then the mana cost (Mana is the blue bars at top left and right, a cards mana cost is the blue rectangle bottom left below the health) A cards attack is shown by the red rectangle directly below the health bar. A card that has a number at the blue rectangle on the right generates mana. This is mostly limited to land.

If you wish to discard a card, click the "D" next to the name.

There is a limit of ten cards per hand / deck.

To win, defeat the enemys cards.

What I am asking is how usable is such a UI on mobile or computer - specifically the methods of summoning, dicarding, and ending turns.