Dreaming of Warmer Days

When Dreaming of Warmer Days is Played,
Choose a Colour. Every time a Permanent
of that Colour is Played, You Gain 1 Life,
Its Caster Loses 1 Life, draw two Cards,
and discard Two Cards, and Tap a Creature
you don't Control and return target Land
to its owner's Hand.
"Say again?!?"