This card is an uncommon. It’s power level is currently akin to a mythic in this game.
In paper, it was a terrifying card to deal with if you got a couple bad flips. I suspect if Wizards reprints it, it will be at rare due to power level.
It’s main function is to increase first card’s cost, however, it needs to be tweaked to better match it’s rarity.
Some other cards that permanently increase card cost or remove mana are Harbinger of the Tides (Rare) and Jace’s Sanctum (Rare). The first card is a one shot on a creature, the second is once per turn on a 2 shield support. There is also Kiora’s mana manipulation ability, but that also costs almost 1k crystals to get if you couldn’t afford her back when she was 550. I’m not including Reflector Mage because the 300 increase is temporary.
I find supports that disable creatures are a little better balanced. Claustrophobia (Common) has one shield. Prism array (Rare) lets you draw 3 cards and only disables the first creature with 3 shields. Hixus (Mythic) should be made a creature, but he also only has one shield.
The issue that is happening is that with decks that are built around card draw, Sphinx’s is triggering with each draw, instead of the first draw of the turn (more in line Jace’s Sanctum), so when someone plays Pore Over the Pages, or activates a card draw mechanic, it basically puts the other player at such a severe card disadvantage that it’s almost worth leaving the match because the end result is a handful of cards that you can’t play in one turn and there is no way to reverse it.
Compared to Jace 2’s Unravel, it’s still overpowered. There are numerous ways to remove big creatures (every colour easier has access to creature removal), but it is very difficult to get cards that destroy supports, especially outside RGW. The card is basically functioning as a Hixus for your hand, disabling your ability to play your hand every turn.
Suggestions to fix the card:
- 1 Shield. It gives the opponent a better chance to destroy it before it becomes impossible to do so because other matches put it in a bottom corner (Similar problem with Hixus).
- Once the support is destroyed, revert all mana cost increases (Similar to Hixus)
- Double its mana cost. (I get supports are supposed to be cheap, but with the scarcity of removal, it’s often a free win)
- Limit it’s triggers to once per turn (Allows the opponent to be able to play some cards while still being a hindrance)
The first two suggestions are fitting for the card, and it still has a similar, but lesser bite compared to a mythic. The paper card was semi-situational, and it helps win games, but mill isn’t a Tier 1 strategy in paper. It needs to be toned down to better match cards in it’s rarity band.