[X] canute
So, remember the little MCU D&D SI idea/challenge?:
The OG Tier List makes it way too easy- too much phenomenal cosmic power.
How to survive, much less thrive, if you can only pick from the literally fourth rate stuff? No Warmage, no Healer, no Warlock, what is one to do?
@Crake in particular seemed skeptical.
This particular proposition kept me thinking, as the deal is supposed to be what
I would choose. You get to customize your superpowers, so what has a by-the-numbers highest DPS or such isn't necessarily best. Would you actually want to live with feats such as Aberration Blood or Willing Deformity? Would you be satisfied with just being real good at bursting single targets down in one round and nothing else?
Still, I think I found a very good balance, and something that'd let you fit in with the MCU: Rogue//Shadowcaster*.
Your chassis is d6 HD, 3/4 BBAB, 8+INT skills with virtually every skill in-class, and all good saves. A bit skinny, but we've got the solution to that.
Rogue is a surprisingly solid class, which requires very little extra input to work, and doesn't rely on super high stats either. 10d6 SA is a lot of bonus damage for each hit so you don't need strenght, 15 BAB should make you a truly excellent combatant, and the skills, at 23 ranks, are a superpower unto their own. The right Profession or two, even Profession (Marvel Scientist) if you can swing it, already makes you able to hang with anyone in the tech field.
Even if you spend all your magical tricks, you are still a CR 20 melee combatant and a (Marvel) world class scientist. More than enough to make the Avengers cut, if that's what you want.
But Shadowcaster really brings spun expectedly powerful stuff to the table. Some highlights, keeping in mind that you get to cast 1st-3rd level stuff 3/day, 4th-6th 2/day and 7th-9th 1/day, each, with a feat giving an extra use of them, and you can pick twice to double uses (so instead of picking "Fireball" and "Lightning Bolt", you pick "Fireball" twice and get to cast it 6/day):
1st-3rd: Flicker (like Garin's, Immediate action teleport), Killing Shadows (10d8 untyped damage in a 60ft cone, Shadow Skin (also Immediate action, DR 15/-- for one round), Quicker Than the Eye (+15 Sleigh of Hand).
4th-6th: Bolster (+100 HP), Fearful Gloom (30ft radius blob of darkness, everyone inside saves vs Frightened), Languor (either Slow or a non-Mind Effecting Hold Monster), Pass Into Shadow (plane shift limited to plane of shadow and out = Cast twice for instant interplanetary travel with endless range), Greater Shadow Evocation (but up to 6th level, still 60% real), Unveil (removes a shitload of conditions, including disease (!) and insanity).
7th-9th: Ephemeral Storm (Wail of the Banshee, but save and still take 5d6), Umbral Body (Ethereal for rounds/lv), Shadow Time (three rounds of Time Stop), Reflections of Things to Come (basically
Foresight), Far Sight (Greater Scrying with a True Seeing sensor that can also detect things like the targets greatest fears and love), Soul Puppet (Dominate Monster).
A 20th level Shadowcaster can have all of these at once, and more as I didn't pick everything out as it's hella late.
Point is, you might have fairly weak stamina with high level shadow magics, but there are many which are more than powerful enough to tilt the balance with a single casting, much less two.
And there is an alternative build: Spellthief//Shadowcaster. Half the SA and no face skills, but gain 4th level arcane spells and many
incredibly fun class features.