Sounds good to me, think the difficult part will be to balance "the randomness"... think if you can fullfill the following conditions
- your main stratgey by the passive cards is most relevant
- if played correctly a "correct play" which adjust for the given level based on right passive card strategy fails only in rare cases
- you can get lucky in rare cases with the offered direct cards (just need to be rare enough to feel quite special)
it might be quite enjoyable... of course playtesting will show that it really works