By now, hundreds of Dragons can be found all throughout the game, and the strongest of them have incredible stats, devastating abilities, and a home in competitive decks in a variety of formats, most of all the Commander format
Can You Respond to Undying
It essentially staples the Swords to Plowshares text onto an enters-the-battlefield effect, which makes for a strong card even when you're just casting it for full price
The flexibility of this ability triggering from non-creature spells means you could very easily run Saruman as an artifact or enchantment commander, opening up interesting deck-building options while keeping to the flavour of this key villain
OK, cool
Theres an argument to be said that it came from an artifact block, so there are more ways to remove it than normal, but it was still an incredible card that I think merits the Top 5