Don't sleep on this one though, it's actually quite solid if you include some tribal synergies and/or ninja's and/or bloodthirst in your cube.
I wouldn't do a one-for-one swap here. Although Jace, Wielder of Mysteries can't protect itself, it doesn't matter as long as there are only 2 cards left in your deck. Jace can mill you for two, then draw a card and win. Jace effectively plays the same role as Thassa's Oracle in the "mill yourself" strategy. While Thassa's Oracle is a superior card to Jace, Wielder of Mysteries in multiplayer, only having one copy of this effect available at a draft table means that the self-mill deck is going to be a greater risk to draft and have a higher rate of failure in an average game.Talking with one of my drafters, he mentioned he really didn't like Jace, Wielder of Mysteries since it didn't protect itself and costs triple blue. I can see that especially in a MP setting where 2-3 people are attacking you. Laboratory Maniac was too fragile for us, so enter:
I like the card as a signpost that you should be milling yourself for value or a spicy win. I also think the opportunity cost is pretty low (1 cube slot) for what it enables.
My question is, do you think a single Thassa's Oracle is a trap in a cube that still encourages self-mill in blue?
How low-powered is this?