For XR, Meltdown can destroy every artifact in play that's mana value is the X paid or less
The other mode with Winter Orb is not to bother locking down your opponent fully, just to operate far better than he can and win the game in a fight with efficient creatures
With interesting mechanics, both new and old
Archon of Cruelty If you want to reanimate, Sneak Attack, and otherwise cheat a creature into play, Archon of Cruelty is often one of your best options due to the overwhelming advantage of eating your opponents board, providing immense card advantage, and pressuring life totals
You could technically use a generic effect like Demonic Tutor to search for a land, but I want to keep this list distinct by including only cards that specifically search for lands
This is one badass spell