Sword of Feast and Famine

Artifact — Equipment

Equipped creature gets +2/+2 and has protection from black and from green.
Whenever equipped creature deals combat damage to a player, that player discards a card and you untap all lands you control.
Equip

Legalities

brawl: banned
commander: legal
legacy: legal
modern: legal
pauper: legal
pioneer: banned
standard: banned
vintage: legal

Rulings

2020-08-07:
You'll untap all lands you control even if the player can't discard a card.
2020-08-07:
You can tap your lands for mana while the triggered ability is on the stack. However, you'll lose any mana you produce this way if you don't spend it before the end of the current combat damage step.

Links

Printings