Slippery, The Sword Snatcher

Whenever an opponent taps an artifact for
mana, gain control of that artifact until the
end of your next turn.
"Behold, we lay a tool here and on the
morrow it is gone. Yea, we have hid up our
treasures and they have slipped away from us,
because of the curse of the land. all things are
become slippery, and we cannot hold them."
- BOM