If your opponent controls a monster with ATK higher than that same monster's original ATK, the ATK of the equipped monster becomes double the equipped monster's original ATK, during the Damage Step only
Prossh, Skyraider of Kher
Counters can be found in all colors so you can include counter abilities in any deck
You might offer the copy to the player whos going to give you the sweetest deal or leave you alone with longest
Both of those cards untap permanents in general which includes lands, creatures, enchantments, artifacts, and even planeswalkers, but many cards specialize in specific permanent types
I try to be as objective as possible when I choose what counts as an alternate win condition in Magic