Jaya Ballard
Oracle Text
+1: Add
. Spend this mana only to cast instant or sorcery spells.+1: Discard up to three cards, then draw that many cards.
−8: You get an emblem with "You may cast instant and sorcery cards from your graveyard. If a card cast this way would be put into your graveyard, exile it instead."
Card Rulings
4/27/2018 Mana produced by Jaya’s first ability can be spent among any number of instant and/or sorcery spells.
4/27/2018 You choose how many cards to discard while Jaya’s second ability is resolving. You can choose to discard zero cards this way (and then draw zero cards) if you wish.
4/27/2018 Jaya’s emblem doesn’t grant you permission to do anything with instant and sorcery cards in your graveyard except cast them. For example, you can’t cycle instant or sorcery cards with cycling from your graveyard.
Her only minus ability is her final. If you have things you want to play, you have extra mana to play them (either directly with her ability, or indirectly as you have free mana for your other spells). If you don't have what you're looking for, dig for it, all while gaining loyalty.
Her emblem is basically a perma-Snapcaster Mage. Every burn spell and spot removal gets double value, every spell you cast with her extra mana gets a second use, every instant and sorcery you pitched with her second ability can get used again.
She seems solid to me. She can come down turn five with 6 loyalty and still let you cast a 3-mana spell that turn. What's not to like?
On a very base level, she has poor synergy with herself, as she wants you to stockpile cards in hand to make use of her second ability, but she wants you to be running instants and sorceries to make use of the first. Jaya Ballard, +1, three lightning bolts? Great, now you've got a planeswalker that does nothing until three turns from now, assuming your opponent doesn't ping her for 1 at some point.
Finally, the ultimate doesn't justify the cost of protecting this thing. Tamiyo, the Moon Sage plays utility and defense right up until she goes off, giving you an extremely powerful emblem that wins you the game without any real effort and isn't replicated by any other card in Magic. Jaya's emblem is Past in Flames. The decks that run past in flames wouldn't touch Jaya.
This card looks comparable in power level to a Planeswalker Deck intro pack foil, and not favorably so.