Simple flicker-based tempo shell with Puca's Mischief as a value engine.
Our basic strategy is to play creatures with useful "enters the battlefield" abilities and then either use the Mischief to trade them for our opponent's better creatures or use flicker and bounce effects to re-use ETB abilities. Ideally, both - Planar Incision and Flickerwisp let us target creatures under our opponents' control, so we can trade and then regain control and re-trigger ETB at the same time.
Note that Flickerwisp is itself an ETB creature and therefore can launder our more restrictive flicker effect, Ephemerate, into one without restriction.
Flickerwisp can also target lands, so we have a couple Skyline Cascade in case we need a big beater to take a few turns off.
Man-o'-War is a critical tempo swing early so we can stay alive, trades for most early threats and is our cheapest creature that's worth flickering just for value. In a pinch, it can be used to recycle other ETB effects as well including taking back a traded creature.
Echoing Truth is unfortunately not a permanent and therefore not interacting with most of our plan but is necessary as a tool against go-wide token decks and also provides a way to protect Puca's Mischief.
There's problems with Puca's Mischief. The tempo loss is immense. Not only is it a four drop, it doesn't do anything until the following turn besides sit there inviting removal, and even then it requires you to have nonland permanents in play in order to start working. That can be a tall order against any aggressive deck, even with Man-o'-War. Pentad Prism solves all these problems - we can accelerate out the Mischief on turn 3, keep up Spell Pierce if we hit our land drops, and then we have a bona fide useless 2-drop right in time for our fist trade. Pentad Prism is so critical, not having one is almost enough to mulligan regardless of lands in hand. I'm still not fully convinced that the optimal version of this deck doesn't include some number of Tumble Magnet for similar reasons. Thraben Inspector and Novice Inspector are lackluster flicker targets but they're better than nothing and we need early blockers badly. Dawnbringer Cleric gives us some utility and trades a little better.
By contrast, we need payoffs at the top end to make all this durdle worth it. We can't rely on Puca's Mischief for victory entirely - Mulldrifter and Enlightened Maniac will do. Both provide a lot of value when flickered and trade quite well. Mulldrifter can of course be "cheated in" off an Evoke cast, which is just about the best use an Ephemerate can be put.
Can't resist putting in one Steel Golem. Even if we don't lock an opponent out with it, it's a great early blocker - of course the danger is that we'll lock ourselves out and it's also a more effective creature than we generally like to give to our opponents, so we'll keep it to one-for-fun.
