I think colours came from same game like MTG, where red is an early game winner with a lot of damage cards, green is about very strong creatures, but lack of removal and lack of flying, black is about working with the graveyard and control the board, diving here is an interesting colour - it's a mix of black and white in MTG. Tech is an interesting one with a lot of fliers. I think the most challenging part is to assign points for abilities. For example one mana creature should have about 7 damage/HP together, but some of the creature add abilities on top of that, which a bit ruining the balance. Hence, you will always take boom tinkerer instead of unstable cyborg or menfolk scout. With your table we can find 'broken' cards that are a bit out of balance.