I imagine its by design, but its a predatory design. When I tap and hold on the gold button to level up a Planewalker, the thing devours my runes at an insane rate, so that its really hard not to overspend on it. I have to carefully tap, tap, tap on it to only go up enough to level up, and then I still overspend a little bit.
I’d say that the button should:
Bring you up to the next level if you have enough on a single press
Or spend all the runes you have if you dont have enough
I’d have to tap it again to spend more to go up another level or spend the remainder of the runes.
For a great example on how to implement this well, follow the Marvel Puzzle Quest model - it increases smoothly, and stops when you level up. There’s also a button for increasing to maximum current level.
I agree that this should be changed. If only from a user standpoint. I usually like to level my planeswalkers at the same time, however, if I level up my Lelianna too much from the speed of this level up button then I don’t have enough for my other planeswalker.
Rather than make me grind more points or even buy them (perhaps as intentionally designed), I simply get too disappointed to play the game further.