Will using Convergent Future give you a critical success if the minimum number you need to hit is 20?

Convergent Future (p185 EGtW) States:

When you or a creature you can see within 60 feet of you makes an attack roll, an ability check, or a saving throw, you can use your reaction to ignore the die roll and decide whether the number rolled is the minimum needed to succeed…

If that number is a “20” does it meet the requirements of a critical success? (p194 PHB)

Is the damage to the second target from the Green-Flame Blade cantrip also doubled on a critical hit?

I’m thinking of a concept of a spellcaster that fight in melee from the moment I re-read the “blade” cantrips (green-flame blade and booming blade), and realized that they can deal a lot of damage. Long story short, I re-read the Assassin subclass, and was thinking about how they interact with critical hits.

If it is obvious that the secondary damage from booming blade doesn’t care about whether or not the initial attack was a critical hit, but how about green-flame blade (which basically gives you an automatic hit on another enemy)? How does green-flame blade‘s secondary damage interact with critical hits?

If I get a critical hit on the attack roll of green-flame blade, is the number of damage dice doubled for the damage to both targets? Or does it only double the damage dice for the first target?

Is a critical failure on a natural 1 a rule or house rule?

There’s a question about this relating to 3.5e, but I couldn’t find one for 5e.

According to RAW, is a natural 1 a critical failure? And if so, under what scenarios does it apply, and what is the expected result?

One of my players is dissatisfied with my calls relating to 1’s* but I don’t have my books handy and I’m having trouble figuring out if the whole shebang is a very popular houserule or actually in RAW.

*I have a feeling that I am likely in the wrong here and it’s more of a same-page issue than a mechanics one, but I want to check what the book’s ruling is before we sit down to have a conversation about it. Our table dynamics aren’t the question here; I just need to know the mechanics to make an informed decision.

Do effects that activate on a critical hit still activate when the hit is against an opponent wearing adamantine armor?

I know from this question a critical hit on adamantine will still hit, but I was curious if the critical hit no longer being a critical hit affects features or feats that depend on it.

An example that came up recently in a kind of pvp session is I had adamantine plate armor, and my friend had Great Weapon Master. One of the effects of Great Weapon Master is:

On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.

Would a critical hit that became a normal hit still activate the bonus action melee weapon attack?

Improved/Superior critical vs Adamantine Armor DnD 5e

Without adamantine armor a critical hit is an auto hit regardless of AC. Though sage advice ruled that a “Improved/Superior critical” attack auto hits when it lands on 18 or 19 BECAUSE it’s a critical hit unlike in PHB where the nat 20 auto hit is an entirely different wording

So my question is would a champion rolling an 18 or 19 on an attack roll auto hit against adamantine armor? I’m assuming it doesn’t since it would take away it’s critical hit status which is the only reason it auto hits.

How does extra damage work for critical hits?

I’m a bit confused on how extra damage works for critical hits. Let’s take the following example:

A thief with sneak attack rolls a crit. I’m under the impression he rolls double his normal attack dice AND double his sneak attack dice. Is this accurate?

Another example, I finished DM-ing my first campaign recently. The Giant Spider enemy monster has an melee attack that causes a constitution saving throw. If the player fails, the enemy rolls an additional 2D8 of damage. In this situation, if there was a critical hit, and the player failed their saving throw, would I also roll double dice on the additional damage? Or is that considered a separate attack?

When a Battle Master fighter gets a critical hit and uses a maneuver that adds a superiority die to the damage, is that damage die doubled?

The Battle Master fighter has access to a number of maneuvers that add a superiority die to the damage roll. For instance, the Trip Attack maneuver says (PHB, p. 74):

When you hit a creature with a weapon attack, you can expend one superiority die to attempt to knock the target down. You add the superiority die to the attack’s damage roll, and if the target is Large or smaller, it must make a Strength saving throw. On a failed save, you knock the target prone.

The Critical Hits rule states (PHB, p. 196):

When you score a critical hit, you get to roll extra dice for the attack’s damage against the target. Roll all of the attack’s damage dice twice and add them together. Then add any relevant modifiers as normal. […] If the attack involves other damage dice, such as from the rogue’s Sneak Attack feature, you roll those dice twice as well.

During our game, the fighter PC rolled a critical hit. He then wanted to use a superiority die to use the Trip Attack maneuver to trip the enemy. Based on the above rules, is the damage from the superiority die also doubled?

I’m assuming the answer is yes based on the last statement in the Critical Hits section, but I wanted to confirm.

Lingering Composition: Does a Performance critical failure cost the Focus point?

TL;DR: The bard player is arguing that lingering composition is a Performance check, and another player is stating it’s Casting a Spell (Focus spell).

I have a player playing a polymath bard with lingering composition.

This player insists that when casting the composition Focus spell, on the composition’s Performance check, a critical failure is the same as a failure, and the bard doesn’t expend the Focus point (because the Focus spell requires a Performance check to determine duration, and lingering composition doesn’t have a critical failure entry, only a failure entry).

My ruling as GM is that the bard is casting a Focus spell, and that the Casting a Spell rule is the active component, not the Performance check.

Lingering Composition: https://2e.aonprd.com/Spells.aspx?ID=389

Casting a Focus Spell: https://2e.aonprd.com/Rules.aspx?ID=276

How does the Great Weapon Fighting fighting style interact with critical hits and the half-orc’s Savage Attacks trait?

We know that the Great Weapon Fighting fighting style allows the rerolling of all 1 and 2s that come from a weapon taking the new roll.

If a player using a Greatsword gets a critical hit and rolls 4d6 damage, does the GWF count for all 4d6, or just the underlying 2d6?

Does a Half-Orc get to apply GWF to their Savage Attacks, allowing a potential 5d6 under the GWF rule to be rerolled on 1 and 2’s?