[2023] New cards

As many people have surmised, the coin cost does not increase the higher it stacks.

It stays at 1. So you could theoretically spend all 10 mana, use 1 spell mana to play the '10-stack coin card' in your hand and recover all 10 mana again. Assuming your Coin doesn't get Pranked or have its cost increased another way >_>

You're correct, max mana would stay at 8, this wouldn't ramp you!