These two spells both blow up artifacts or enchantments—classic Disenchant/Naturalize effects with Time Spiral twists. But check out the cards' art—in each piece, the same sword is being destroyed. In Return to Dust it's crumbling into particles; in Krosan Grip it's seen with the "jump-cut" split second visual cue between shiny and whole on the one side, and rotten by nature on the other.
But look closer. The swords were illustrated by different artists and vary on a couple of details, but obviously share the same design. Here we've rotated Wayne Reynolds's Return to Dust piece ninety degrees so you can focus on the similarities.
What's the meaning of the same sword appearing on these two Disenchant effects? How can the same sword be destroyed multiple times? It's a mystery that may be solved sometime in the future.