haha. great questions.
Id say the closest to an outside the box strategy is the backfire ability which damages the attacker if they miss. The riftwing in the death splinter has no attack, but a high speed and flying which makes it tough to hit with ranged or melee. You'll need it at lv5 to get backfire which should cost you less than $10 but you'll need a lv.4 death summoner to use it which could cost $200 or something.... not to mention the fact that you'd have to battle your way to silver league before you could even use a common card at lv5.
Basically, its genna cost a fair bit to get to the most fun strategies, but prices are as low as theyve been in a long while right now, and as long as your prepared for a bit of a grind, you can always earn your way towards better cards. Maybe test out some decks by renting first and see what works for you