Testament is fundamentally flawed in this patch
At a decently high celestial level, Testament feels so taxing and heavy to play as that I wonder what the devs were thinking even putting a character in this state in the game. I don't think Testament has a single strength that another character does better, and even the amalgamation of all their tools doesn't strike fear into a savvy opponent that knows how to fight them. But their weaknesses are some of the worst of any character of their type or any character in the game.
The addition of Wild Assault buried Testament even farther than he already was from Season 2. As they don't benefit from Wild assault's pressure nearly as much as other characters and other characters want to be right on top of Testament, so it's a double nerf in one patch. To be able to zip across the screen actually GUARANTEES some character's win con, while it only slightly increases Test's chances of victory.
Some very GLARING weaknesses when I play Testament:
2P can be 6p'd: and low profiled by kicks like Jack-O's 2k and Happy Chaos's 2k. Being Testament's only 5 framer and being DPless, I can't see why he has a 2p that is this bad. Kyle has a similar 2p, but he has an invincible reversal, so I see why the trade off is there. This means if you get pressured there's almost no way for you to fight back unless you use system mechanics.
Their zoning stinks: Testament's zoning has so much risk associated with it that it can't be called zoning in good faith. Baiken's f.s can CH Test's f.s, not due to the speed but due to the hurtbox on all of Test's moves. It is very difficult to keep a savvy opponent at bay, nigh impossible.
Calamity One is one of the worst reversals in the game: I just can't see why this has a 15f startup. Axl, the tried and true actual zoner has a 12f startup reversal in sickle storm. IDK.
Atrocious active frames: You really feel this against the Johnny's, May's, HC's, but any character can really do this. Most of Testament's key buttons are 2-4 frames active, which means they are very easily backdashed and very easily beat by more active buttons. To call out a backdash you either have to risk your life by dashing in fully or pressing a 23 frame button in 2h or 6h, which are alright on block to extremely negative on block.
No non-death movement options: Possession is basically unusable. It's just too risky. Testament doesn't have something like a Rainwater, or a Ram flip kick, or a Johnny flip to make the opponent act. This wouldn't be so much of a problem if almost everyone else in the cast didn't have one.
No degeneracy: Testament is what people think Kyle is. A bread and butter, bland character. They can't zip across the screen. Can't low profile scum dipper you, or low profile stroke you, or jump over your f.s with a vault, or command grab you into a instant high low. Can't bite you, can't loop heavy dolphins into deadly strike throw, can't put you into +3 close slash hell, can't put you into some disgusting fuzzy on knockdown, can't summon a minion into super and crank your risc to death. Can't freeze time, can't instantly shoot you from across the screen. Testament is literally a street fighter character that got ported over into strive and was given arbiter sign as a fake version of an overhead or low to be made into a strive character.
I'm not saying Testament can never win a game in Celestial, I'm just saying that against someone of your skill level, you're ALWAYS going to be even at best, and losing at worst, no matter the character.