Was inspired to make a card that only looks like it's doing nothing.
Creature- Human Cleric (R)
At the beginning of your end step, exile each exiled card face up.
For those who are unaware of how this thing works. 406.7. If an object in the exile zone becomes exiled, it doesn't change zones, but it becomes a new object that has just been exiled
In other word, this hoses adventures, suspended cards, foretold cards, cards acquired through impulse effects, cards that put counters on exiled cards (like mairsil or draugr necromancer), cards that are exiled and can be cast later (such as those taken with Gonti), and so forth.
Should probably say "exile face up" so that any cards exiled face down are turned face up. The rules probably do that automatically, but putting the clarification on the card for such a niche effect is probably wise.
It doesn't do enough for 1W, as the exile effect is so limited. Should probably have lifelink, vigilance, first strike or some combination of those.
I agree with rowanalpha, it needs a key word and should mention the face-up fsce-down status. But I believe it should turn them all face down. This hoses slightly more effects and makes it obvious something is being done rather than hiding its actual effect in the rules. Though it will still seem hidden when effecting already face-down cards.