RESTRICT: Cards that are non-permanents that causes you to draw and net 2 or more cards than mana spent to cast, through any method of casting via the card itself, in the same turn.
Rationale - Cards that allow you to draw and keep a significant amount of cards relative to the mana spent to cast it is unfair in that the card advantage gained via that one spell is often insurmountable. (This rule would hit things like ancestral recall, most wheel effects, and gush, but releases ponder, preordain, brainstorm, etc., and doesn't hit things like harmonize, bazaar, necropotence, etc. - probably hits PO and ad nauseum) Some cards like Enter the Infinite are likely caught in this too. Maybe a qualifier could be added to the rule, like "costing less than your starting hand size."