For Omens it gets a little complicated because there is no cost. Maybe rank them in stars or something and limit the total amount of summed levels of Omen that a deck can contain in its construction?
Whoops! I forgot to mention Omens in the post (I've update it now). Omens should be balanced against Omen abilities in Mork Borg. However, that sounds like a cool system and I totally endorse developing it as a variant if you want to.
