Light and Shadow versions are, but the non-shadow versions have a bit of a startup period. They also have their attack boxes sort of off the ground so moves that low profile can go under it and not get hit by the move at all, causing a whiff.
Non-shadow versions are all 9 frames startup, and shadow is 2,5. And yes, despite 9 frames being a lot longer startup than most invincible DP style moves, he is invincible completely on lk Fireflash until active frames, with the exception of a move outprioritizing the attack box on it, considering the move priority hierarchy.
Cinder’s options against Omen are definitely the favored in this matchup, at least in my opinion, so take that whatever you feel it’s worth. Between Inferno being able to neutralize your fireballs somewhat, the upper angled version preventing you from flying in at range, and the lower version covering your approach by slide kick, smart Cinder’s are going to keep you covered, and if they have shadow, they’ll try and follow that up on hit into a combo, since it’s a super easy confirm. Even if they are caught airborne, it’s not hard to juggle for a cashout or recapture.
I’d say though, unless he wants to turtle and force you to come to him through inferno, most likely he’s probably going to rush you down or try. An impatient Cinder is going to try and come at you with trialblazer, without thought. Air to air, j.HK will knock him around like a ragdoll, and is super effective against aerial trialblazer. If he’s impatient, remind him of the knockback properties on that kick.
Pretty good advice. Just be aware of shadow trailblazer and you’ll be fine, it covers better ground than most people give it credit.
Cinder is pretty + on block on ALL other his shadow moves, but shadow counter can help with that. Unfortunately, it’s really difficult to time shadow counter on both shadow inferno and shadow fission. They’re multihitting moves that hit more than the average 5 times most shadows do, making it difficult to keep track off and time a shadow counter. If you choose to block instead, which might be wiser, Cinder is gonna have the opportunity to move first, don’t be baited into think you can throw him off a blocked shadow trailblazer. That one is the only reliable one to shadow counter, but even it on block leaves him at +4. I’ve seen a LOT of people fail to realize this and almost all of them fall prey to a frame trap.
Do not shadow counter light third degree combo, EVER. It’s a trap. All shadow counters lose to hits two and three. They’ve said before there is now a universal 8 frame startup to all shadow counters, but the second and third punches of a light third degree break that easily. Every punch of light third degree has 4 frames of startup, you’ll never shadow counter this one, don’t fall for it. Medium and Heavy third degrees are more reliable to shadow counter.
If you wanna beat him, you’ll have to make him afraid of using Fireflash, and like @FallofSeraphs76 said, bait it out and after a few times of being mislead, you’ll be able to apply your pressure more easily. I’d also recommend using your shadow tracking fireballs on their wakeup to keep the best pressure possible, they won’t want to use fireflash against you if they know they are going to get knocked out of it by a fireball.