Just because this is minmax, I figured some combos are in order. Just assume anything from outside the class is given by another party member. Or that you don't listen to TenJ about anything.
It's good to find the busted stuff. I gave that kind of feedback on the previous two mystic iterations, and it would seem enough people did the same to push a feature like Strength of Mind from level 1 to level 4 on versions 2 and 3. Figure out what's ridiculously powerful and report it if you want the final version to be balanced (or don't if you like unbalanced stuff). Don't be shocked there's powerful multiclass interactions because they've outright told everyone they don't think about that until the end of the design process.
Visions of Disgust and Conjure Animals. Those itty bitty beasts don't look so weak now that they're causing an auto-d6 of psychic damage each turn. A 1min long placable AoE is pretty nice. Especially if you stack tiny creatures or swarms on the BBEG. 8d6 to begin with, but can scale all the way to 32d6 as a lvl9 conjure for massive DoT. No attacks, barely anything resists it, one failed Wis save and the mental pain occurs. Why did it have to be snakes?
There's no way for players to get swarms without some real stretches of RAW, and RAI is that swarms aren't legal for just about anything players do involving beasts. Cows are the highest damage CR 1/4 beast one could summon with Conjure Animals iirc, but there's a case for Velociraptors with their Pack Tactics. Flying Snakes are pretty good for CR 1/8 but you don't want to keep them close to an enemy. Cows are the toughest things to just leave next to a bad guy unless he can use fireball or something equivalent while excluding himself from the effect.
Iron Durability focus and Bestial Transformation (Thick Hide). A lazy, casual +3 AC for an hour that stacks with most things, no concentration needed. Completely worth dipping the class for, just for two hours a day of this (despite what TenJ says about dipping UAs). Damn nice for a mono-mystic anyway for 2pp. Combining this with Cloak of Air makes you incredibly difficult to hit with attacks for ten minutes, though it'll use your concentration and 5pp at mystic (3) to run it.
Those are more relevant at higher levels, since nonmagical AC scales against CR-appropriate attack rolls about as well as a non-proficient saving throw scales against save DCs.
There's limited scry and die available in the class, or rather, scry and teleport and kill. Nomadic Mind has a couple of powers that aren't too bad for the finding or seeing part of that (they're good because you can "mentally see" with the sensor, while still retaining your normal vision). Then just Phantom Caravan the whole party in on top of them if they're within a mile of you. Or an entire army eventually with Nomad's Gate cubes. It's not that much different from a high-end mage, but it's there in Mystic as well. At a relatively early level and at a cheap price too.
(The whole Nomad discipline set is what keeps the class really relevant at higher levels imo, though Awakened is nice too. There's lots of nice control/damage/buff spells available elsewhere, but some of the Nomad stuff is quite hard or expensive to do with other classes).
Some of the blasting is decent, but agreed, those disciplines you mentioned are the gems. The blasts are alright because a lot of the capstone blasts have conditions attached.
Nomad's Gate is essentially a Portal gun, but only for creatures. Which is a pity. There's a lot of stupid stuff to do with it though. Everything from creating the exit cube 1 mile up in the air and having someone push the BBEG through it (splat!), to dropping them to the bottom of the ocean and ceasing concentration (Bond villain villain death). Watch some youtube vids and see if you can recreate them in DnD.
It's comparable to Arcane Gate, though it lacks some of the in-combat shenanigans of Arcane Gate since Arcane Gate can be made invisible from one side. Nomad's Gate is far superior for range though.
Not actually a combo (because I haven't worked out anything to combo it with yet), but Cloud Stairs doesn't have a range noted. Which means it's "anywhere you have LoS to" I guess. Good for instant siege towers while you command from the rear, but there's gotta be more to do with it than that.
It also doesn't say it must be an unoccupied square. If that's intended, it's potentially a superior Levitate if the staircase forms from the ground up or you put the stairs on top of or around a target to keep them from moving. The ability says they're solid.
Blind Spot = very nice. Single target Invis as a ++ version of True Strike and Hide. Dip target for sneaks. Expect some muted cries of borkny.
Delusion = single target Minor Illusion = classic from previous editions. Very nice anyway, especially since it shouldn't be obvious you "cast" it. No wonder I rolled 20 earlier.
Considering you give off 0 indication to anyone watching that you're making these things happen with no limitation on how often they can be used, it would be amusing to RP a mystic as the biggest douchebag in the world, or the most enlightened 5 year-old prankster.
"I've tapped into the deepest powers of the mind to give people surprise wedgies and to make them hear fart sounds whenever they try to listen to someone else talk."
