Zhuangzi, the Vague Scholar

Minnow's Suggestion: As long as Zhuangzi is on
the battlefield, artifacts can be tapped in place
of mana for spells and instants.
Excellent Gourds: When Zhuangzi enters the
battlefield, target player can discard one card
from their hand and replace with the top card
of their deck
"How do I know this is so?"
-Zhuangzi, Chapter One