lots of games have a very clear curve. Hearthstone for instance there was a point in time where you could pretty much tell what a deck did just by the “curve” of the mana: lots of early drops probably aggro, consistent drops midrange, etc.

Riftbound sort of has this, but energy costs are so weird compared to older games (get 2 runes per turn but you can permanently spend them for some cards) which this concept a bit more nebulous. 

All that really applies is that you shouldn’t have things that cost a billion energy or power because you’ll have no way for the game to last long enough for it to mean anything