User from OwnedCore suggested this for Mana Accumulation:

When you do actions, you get more mana..

I'll give you an example
Player 1 checks + 1 mana
Player 2 calls + 3 mana(edited)
Player 1 calls + 1 mana
Player 1 = 2 mana
Player 2 = 3 mana
Player 2 uses a spell for 3 mana. Gains more money but he cant call for 2 rounds
its fair

Basically his idea is, the more aggressive you are, the more mana you accumulate..

My worry is that you could become over powered by just being reckless and then you always have more mana than everyone else and you can cast more spells..

His suggestion for pre-flop vs post flop. Pre-Flop spells should be gambling related..

Example: . So you click the Double check option. This means if someone raises the stakes next round you will auto call for two rounds but receive 50% chips should you win that round.
If no one raises it. You will still just check twice but receive your 50% reward should you win.

So if you cast this spell, I think what he's saying is that you are forced to check for 2 rounds, but if you win that pot, it gives you 50% more.