Vanellope von Schweetz - Sugar Rush Princess isn't a Legendary card, but it can still be highly useful in the right deck
Even without the token making which only scales up as the game goes on Triceraton Commander would be worth looking at for those decks just as a way to get more dinos over blockers
Played as a standalone card, its not very good but the ability to represent a lot of threats without additional mana investment makes me think that this has a very high ceiling
Tezzeret's ultimate ability allows its controller to draw a card every time they tap an artifact
Tims Zuran Spellcaster (Ice Age/Alliances) , Suq'Ata Firewalker (Mirage/Visions/Weatherlight) , Rootwater Hunter (Tempest/Stronghold/Exodus) , Thornwind Faeries (Saga/Legacy/Destiny) , Stinging Barrier (Masques/Nemesis/Prophecy) Psionic Gift and Hermetic Study are fine, but they require a two card investment: the creature you are enchanting, and the enchantment itself
They can only take one or two hits each and aren't very good for attacking (or 'Challenging') your opponent's cards, but they cost a mere one Ink to deploy, meaning you can drop them on turn one