@Trymantha:
Short Answer: Yes, it works with unearth if you time it right.
Long Answer: Abilities that say "the next end step" are due to trigger just once, whenever that step is met. Once it has triggered it will not trigger again, but that doesn't mean it has to resolve. Activating the
Sundial while the Unearth trigger is on the stack will exile the ability and leave your creature on the battlefield (It will still be exiled if it would later leave the battlefield).
Another note with the sundial, ending your turn before such an effect has the chance to trigger means it will still trigger at the next chance it gets. Ending your turn before the end step means any abilities that trigger at the next end step will trigger at the end of your opponent's turn.
@Robert Merlow:
Short Answer: The last player to do something usually receives priority when they finish doing whatever it was.
Long Answer: If Player A activates a planeswalker ability, he will maintain priority. Player B cannot respond until Player A passes priority. When actually playing in tournaments it is assumed that Player A automatically passes priority unless they specify otherwise. After Player B casts a
Lightning Bolt aimed at
Jace she will also maintain priority. Once the spell resolves the active player (Player A) will always get priority first.
That said, I feel obliged to point out that if Player A's Jace has 3 loyalty and the +2 ability is activated, Lightning Bolt will not be able to kill Jace. Changing the number of loyalty counters on planeswalkers is a cost of activating the ability, not a result of it resolving. Therefore Jace has 5 loyalty before either player receives priority after the ability is activated.
Into the Roil will still return Jace to its owner's hand, but the ability sitting on the stack still resolves as normal.
@Everyone:
Some of these explanations seem a little complex. If I've confused you (or you think I've slipped up somewhere) please don't be afraid to ask.