Scion of Draco Despite costing 12 mana, Scion of Draco can be cast for effectively 2 mana, thanks to triomes and Leyline of the Guildpact
Also, as head designer Mark Rosewater once noted, the Ravnica: City of Guilds set was the first to make in-game factions highly cohesive and distinct thanks to their official names, watermarks on cards, and many cycles
Up the Beanstalk Up the Beanstalk would be playable even if it didn't draw you a card when it enters
Damage could go on the stack of course back then which really helped the card
For example, if you play fetch lands like [c]Polluted Delta[/c], you can play [c]Brainstorm[/c], draw three cards, put your two worst cards on top of your library, then shuffle them away by activating Polluted Deltas ability
She's a fun ramp, card flow win con combo for tokens, a beloved archetype in Commander and elsewhere