Is America Chavez good?
I would say, yes. I do think the overall community is too harsh on her. Certain champions are like wine: it's only after some time you can appreciate them. Immortal Hulk received overall negative reviews in the beginning as well, but since folks discovered he can cheese some content he has been steadily rising in the rankings. I think America Chavez is similar.
With that perspective, it is true she isn't competitive in the current meta.
1) Her sustainability is low
With 3,022, America Chavez has even lower block proficiency than Purgatory and way lower than middle-to-the-road Archangel (3,734). This means she takes a lot more chip damage from parrying. Yes, luckily she doesn't need parry to be able to heavy attack, but parry is still such an essential part of the game.
She really needs a bump there, as nothing really motivates why this should be so low. Certainly with that below average health pool you get the feeling she is a delicate flower who can't take a hit or two.
America Chavez has some energy resistance, but I must say: it is not impressive. With 3 unique Parallel Dimensions, she has 859.08 Energy Resistance, 1,288.62 Energy Resistance with the signature ability.
The Dark Dimension gives her the ability to reflect 40% of the damage taken back, capped at a certain amount. Well, I feel it is useless. Defensively, the dumb AI is incapable to heavy interrupt a special attack, so there is a low chance you will ever have to deal with it. Offensively, if you mess-up, it will not save you in any way. It's not like the 40% is actually a damage reduction, it's solely reflection. It's no Mysterio's Reflective Gas, you don't get a regeneration afterwards.
But let's say it did reduce damage by 40%? Would that be OP? Certainly if you can stack three of those. 120% reduction would mean a form of invulnerability. Well, no, as there is this damage cap. Basically, it would make that you can only lose 15% of your max health. That's the same protection Symbiote Supreme has. So this begs the question: why wasn't this added in the first place? It would make her that extra attractive, as she would be able to tank SP3's with it.
There is a synergy with Ghost Rider and The Hood that allows her to regenerate 30% of reflected damage. It's a nice addition as a synergy, with the cap it means you can regenerate maximum 4.5% of your max health. Nothing too game breaking, in my opinion.
Lastly, Dark Dimension SP2 effect makes that the last three hits regenerate 12% of damage dealt. While running suicides, if you're lucky with the crits, this is a break-even with the recoil damage. Without suicides, this is a lot less. Compare that to Claire, who has more consistent crits and heals 35% of hit damage. Would it be game-breaking if she would heal between 15% and 20% hit damage?
2) She can't nullify buffs
Not being able to nullify buffs is a strong limitation for a Mystic. Especially for buffs she doesn't or can't reduce the buff potency (prowess, unblockable, unstoppable,...). But she does need buffs to gain more damage, so whatever it is, it should be available only when you want or need it. But how?
Then it hit me. Scroll back if you need to, but for the SP2 there is one Parallel Dimension that has ZERO use: the Negative Zone. Sure, maybe Kabam will add a highly-specific node that requires you to have an Unblockable Special Attack to have some benefit. But for now, I can't think of any. Unless you do a parry, your first hit will just hit the block and deal reduced damage and the other three hits are just regular hits with no extra effect (besides Big Bang Dimension).
Three hits... Per hit there could be a 100% chance to nullify one buff. Simple solution.
It isn't much, but it beats nothing. It is at a SP2, so it isn't the most accessibele of nullify abilities (SP1 isn't the option as it is part of the main rotation and SP3 just takes too long). If you don't need it, then you don't activate Negative Zone as last dimension. If you however do, there you have it.
Last one is highly specific, but fitting. When she activates Negative Zone, she should remove the Cosmic Rod from Annihilus. It makes sense that when she accesses the dimensional energy from the Negative Zone, she can counteract Annihilus thus removing the Cosmic Rod.
She has a synergy with Longshot and Mojo that allows her to reduce the duration of Unstoppable buffs by 50%. But then again, if you've those in your team, why bother with America Chavez at all? One of those things that baffle me: developers give these unique synergies to correct flaws in champions, with synergy partners that do the job better without the synergy. So why bringing these champions in the first place?
It's not because she can't nullify buffs, that she shouldn't reduce their potency. Kabam chose to make her Utopian Parallel Dimension a copy-paste of Dragon Man's Ineptitude debuff. While defensible, there are many more buffs (prowess, resistance,...). Not being able to nullify or to make use of Mystic Dispersion is a big handicap, but limiting her only buff control way to four is not balanced. It should be expanded to any buff who's potency can be reduced (except Power Gain and Regeneration, later more about that), or at least Prowess, Physical Resistance, Energy Resistance and Critical Resistance.
3) Her damage needs a massive bump
A good thing is that her base stats are not an issue. Her stats aren't top of the game, but they aren't bottom either. I do not see any reason why her Attack Rating, Critical Hit Rating or Critical Damage Rating should need a tweak.
I do not think the Dimensional Energy Infusion attack bonuses are wrong, it's just in a match-up with no buffs it is underwhelming. She actually just needs one extra Parallel Dimension. A new one? Not necessarily, there is one already in her kit: the Big Bang Dimension.
The Big Bang Dimension is only activate during the last three hits of the SP2. But what if you could get a 30-second Big Bang Dimension? The SP3 is perfect for this: currently it has no use at all (besides activating 3 Parallel Dimensions, which you can do for a lower power cost and with greater effectiveness with the SP1-SP2 rotation). This is also great for longer fights.
Let's recap what Big Bang Dimension does: every hit deals 50% of hit damage as a burst of Energy Damage. So not only is your attack rating boosted, you instantly deal +50% extra damage per hit!
I doubt you can rush fast enough to get another SP3 to stack another 30-second Big Bang Dimension, but a SP2 might be possible. For the final three hits, you activate another stack of Big Bang Dimension temporarily, boosting it to +100% of hit damage as burst of Energy Damage.
But even taking the numbers into account, I haven't seen much good numbers from the SP2. With four hits that deal 1,170, 1,170, 1,170 and 2,340 for a R5 5*, it literally makes me want to cry. It feels like pillow hands. I believe Big Bang Dimension needs at least a +50% Prowess bonus on top of the burst damage. That or increased critical hit rating, so you can have those big yellow numbers.
And why is the Big Bang Dimension only during the last three hits, and not all four hits?
4) She can use more general utility
While she has solid utility, it's also highly specific and not really unique or exciting.
Regeneration is overall still more prevalent than Ability Power Gain, and thus more valuable utility-wise. Negative Zone should also reduces healing and Regeneration effects by 60%. The icon could change from power drain to petrify.
America Chavez is in some ways an anti-mystic champions. A lot of mystics have Ability Power Gain, which she can reverse. However, she still can trigger buffs. Maybe she shouldn't be able to trigger buffs? She can have an in-build Dexterity with a consumable Precision Passive.
Same thing with Parry. Why not disable Parry on her, and give an in-build Stun Passive of 1 second? Even more, for the duration of any Stun Passive, she passively decreases Combat Power Rate, healing and Regeneration effects by 30%. This makes her suitable in match-ups where debuffs are punished or shrugged off, like Masochism, Kingpin, Agent Venom, Rogue,...
The most valuable general utility is power control. She currently has none. A lot of Mystic champions do have some. Why not add a -15% Combat Power Rate to the Negative Zone Parallel Dimension, for a total maximum of -100%? Also, raise the Combat Power Rate reduction of the Heavy Attack from 25% to 30%. Also, pause the Stun Passive for the full duration of the Heavy Attack. Doing so, you have a base Combat Power Rate reduction of 60% during the Heavy Attack, and with 3 Negative Zone Parallel Dimensions active, this goes to -100%. This means Heavy Attacks generate no power.
5) She needs more practical usability
It's always nice if things fall together. It's those little things that makes a champion more pleasurable to use. America Chavez has such thing, the mid-combo stun when executing a Heavy Attack, but she can have more.
Special Attacks these days are becoming longer and longer. This is detrimental to time-sensitive champions. Kabam has added the feature that during Special Attacks, certain effects are paused. Why doesn't America Chavez pause her Parallel Dimensions? I would like to see that her Parallel Dimensions are paused during any Special Attack, and while performing her Heavy Attack. This reduces stress considerably.
Nothing in her kit says otherwise, so the activation of the Parallel Dimensions or the mid-combo Stun Passive during Heavy Attacks can fail due to Ability Accuracy reduction. In any match-ups where Ability Accuracy is reduced (like Crossbones), I wouldn't risk getting a combo in the face because the Stun Passive failed to apply. Or worse, building up to a SP2 and realising the Big Bang Dimension didn't trigger. Why don't make those interactions unaffected by Ability Accuracy reduction?
Currently, her Dimensional Energy Infusion is entirely invisible. There is no way knowing what damage bonus or how much resistance she has. It would be nice to make it visible. There are two options: she activates a Fury and Energy Resistance Passive. Or, she has an unique Dimensional Energy Infusion Passive. The latter makes her ability active list not so crowdy, while the former can have interactions with all kinds of nodes. Of course, activation of those passives should be unaffected by Ability Accuracy reduction as well.
Conclusion
America Chavez is a peculiar Mystic and the second best Mystic of 2021 (after Sigil Scarlet Witch). With some changes, she can become the best of 2021 and be a worthwhile Mystic to have in your roster.