If your rival had responded to your Unsummon with another damage-dealing spell, your rival could have opted to have that last spell take effect before your Unsummon , giving your creature the deep-six
But for a 2-drop, 3 turns is plenty of time to hit the field and have a significant impact
If everything goes right, and Jace resolves, he will enter the battlefield with 6 starting loyalty, due to Doubling Seasons effect
Its incredibly unexpected and will be sure to garner quite a few Wait, what does that say? reactions from your opponents
Aether Refinery Branching Evolution Corpsejack Menace Corpsejack Menace Devouring Hellion Doubling Season Dragon Broodmother Feaster of Fools Galloping Lizrog Innkeeper's Talent Loading Zone Marrow Chomper Mycoloth Predator Dragon Preyseizer Dragon Primal Vigor Selesnya Loft Gardens Shang-Chi, Martial Mentor Struggle for Project Purity Tainted Adversary Tar Fiend The Earth Crystal Thorn-Thrash Viashino Vorinclex, Monstrous Raider