My suggestion is to limit maximum tokens can be gained in one round.
What is this for?
Nowadays we can't afford full usage of different keywods simulatenously, because every keyword needs your handful of it for maximum effect.
If we limit it to 3 or 4 cards, for example, we can freely use two keywords fully.
To balance this limitation, token per card gaining can be tuned up.
Secondary, i think it is clever to attach additional keywords to existing cards - this will improve their deck versatility.