L - LIGHT
Sentinel's L attacks nullify low priority projectiles.
St L (70k)
Best used exclusively for punishing unsafe stuff since its sentinels fastest normal, its also one of two normals with very underwhelming hit boxes and no armor. Nullifies low priority projectiles.
Cr. L (70k)
Sentinels second normal with an underwhelming hitbox, this is best used for punishing unsafe moves and ticking into his command grab up close because when your opponent is within range of this move, their normals will more often than not beat out yours. Nullifies low priority projectiles.
J. L (75k)
Now were getting into the really nasty normals, sentinels j. L might look underwhelming at first sight, but don't be fooled, its his fastest air normal by a wide margin and as such can be used to punish air throw happy opponents, and since its chainable into a j. S it can be option selected into the ground bounce which leads to a nice fat combo. Plus at low altitudes it coves a very pesky area directly below sentinel where it can be chained into a cr. H for a full combo. It is also used to apply flight pressure and can lead into a tick throw set-up. Nullifies low priority projectiles.
M - MEDIUM
Sentinel's M attacks nullify medium priority projectiles. s.M and c.M have super armor, allowing them to absorb one hit without being countered.
St. M (100k)
This move has super armor from frames 6-15, and nullifies medium priority projectiles during active frames. One of, if not his best ground based normal, works as a really good anti-air, only hits once(so it doesn't scale like cr M) and it has very nice range, although this range can become an issue since a max range st. M will not chain into a st. S. Plus it can be flight cancelled into a combo using specific assists, like hawkeye's, magneto's, and akumas to name a few(st.M +Assist, Flight, J. L, J. M, Unfly, J.M). Be careful though, its relatively unsafe on block depending on your spacing, but a cancel into rocket punch HSF will make them weary of punishing it consistently, and it will whiff on some crouching opponents if your right next to them. But at that range, you really shouldn't be hitting buttons with sentinel to begin with.
Cr. M (97,600) 3 hits
Super armor from frames 6-15, and it nullifies medium priority projectiles during active frames. This move is an odd one, its sents only low attack, so if your trying to convince the opponent not to just block high you'll need to throw this out every now and then. With that said, whiffing this move is death, guaranteed, every time. You whiff, you might as well unplug your controller. In my experience though, I've found an effective way of using this move is toss it out after an air series into a st.L, even if they push block the L, the M should still hit(Im still testing this out) plus it allows you to either go for the cr.M or command grab, a solid 50/50. Also, this move is especially good on small characters since often they can duck St. M.
J. M (100k)
This is hands down one of the best air to air normals in the entire game, the sheer amount of screen this move covers is completely obnoxious, especially when paired with the fact that sentinel can get a fat combo off any hit confirms using this move. And you don't even require amazing reactions to hit confirm, simply double tap M and if the first one connects, it'll chain into the second one automatically, giving you time to see whether its hitting and continue with an S or cancel into flight if blocked. Just an all around amazing move in general, and it also nullifies low priority projectiles.
H - HARD
Sentinel's s.H and c.H fire a beam of energy from Sentinel's mouth. s.H chains into c.H. The mouth lasers form the foundation of Sentinel's long range gameplan. Paired with the right assists, the mouth lasers alone can provide a strong zoning game.
St. H (102,300) 5 hits
Another really good "normal" and one of the best projectiles in the game, sentinel is blessed with a high durability projectile that he can call assists while using, unfortunately this comes at a price as a vast majority of the cast can duck his st. H (some can even stand under it) and can even duck his cr. H. From rocket punch range it can be chained into a rocket punch HSF cancel for decent damage and from full screen can be chained into a HSF DHC into any instant full screen hyper for the cost of 2 bars and about 500k damage. But while this allows sentinel to zone, do yourself a favor and avoid spamming this move without much thought, in a game with characters as mobile as magneto, and teleporters, one badly placed spit could easily lead to a dead sentinel.
Cr.H (102,300) 5 hits
Not much I can say about this that isn't reflected in the st.H discussion. Remember that small characters can duck this move and punish, so canceling into flight or H Drones can cover you and make you safer.
J. H (110k)
Another exceptional air attack, this one is more suitable for applying air to ground pressure. Its a ridiculous +21 on block, so sent is pretty much free to do whatever the hell he wants after an opponent blocks this, and since it +25 on hit more often than not you'll have enough time to visually confirm that the move connected, land, dash in and continue the combo. Paired with a good assist and flight cancels you can keep your opponent blocking in the corner for an entire round until they get complacent and eat a command grab. Nullifies medium priority projectiles.
S - EXCHANGE
St. S (120,000)
Super armor from frames 12-21, nullifies medium priority projectiles during active frames. An alright normal, and one of sentinels safest on block, I don't use this much outside of combos with the rare case being when I have a read on a teleporting dante I use this as a punish occasionally since it leads to more damage than an air throw punish. Other than that I use this exclusively for combos.
J. S (120k)
The infamous frying pan, probably the most hated move in the first month of vanilla, the hype behind it has sorta died down now that people realize how slow it really is. Being sentinels slowest air normal, plus the only one that can't be canceled into flight or hard drive you shouldn't make a habit out of throwing out the frying pan. Its usually best tagged to the end of his other normals(i.e poking with j. M chained into S as opposed to just raw S). But its still a very good air normal, covers a very wide 270 degree radius around sentinel and causes a ground bounce on hit leading to a dead character in most situations, this move is not to messed with. Just don't spam it at every given opportunity or you'll find yourself at the end of many an air throw. Nullifies medium priority projectiles.
All of Sentinel's air attacks (except j.S) are double-jump and flight cancellable.