Since the card is currently only being played in just one modern deck, I personally had it in the third spot behind the best blue reactive spells in the format, Counterspell and Force of Negation, but I can see the number one spot going to the best and most efficient threat the color has to offer
That's what happens when you combine Tinker (which could get out the Jar almost immediately) with Megrim (so that your opponent would take 14 damage from a single Jar discard, assuming they could not play any cards in time)
At face value, it seems like a good Limited card, which it is
Since infect puts -1/-1 counters on creatures it deals damage to, this allows Yawgmoth to act as removal so long as you have a sacrifice outlet
Thwart the Enemy and Obscuring Haze You know what
Many of the cards force your opponents to discard cards, or support reanimation strategies