Duress I card I associate both with old school formats like extended but also a card suitably balanced that it has seen countless reprints making it modern playable and periodically a standard card too
Three Ruby and three Sapphire, a 50/50 split, just like the other deck
To tell if a Magic: The Gathering card is rare, look at the set symbol located on the bottom right of the card: a gold colored symbol indicates a rare card, while black is common, silver is uncommon, and orange is mythic rare
If you don't tap any creatures (including if you don't control any), X is 0
There are a few different ways we can do this, but a super straightforward example is we play Kami, get Sleep-Cursed Faerie in the graveyard, and exile it to Agatha's Soul Cauldron to put two +1/+1 counters on Kami