A natural roll of the attack dice is just the number rolled before any adjustments are applied.
Even: Refers to even numbers (e.g 2,4,6 etc)
Odd: Refers to odd numbers (e.g. 1,3,5 etc)
Brace For It
Trigger: Any missed melee attack against you
Until the start of your next turn you benefit from having the Defense Fighting Style (+1 AC if in armor). If you already have this fighting style, the bonus doubles to +2 AC. In addition, you reduce the first critical hit you take in this time to a normal hit.
Building Fortunes
Trigger: Any natural odd attack roll.
Your critical range for weapon attacks increases to 19-20. Each time you roll a natural odd number to hit with a weapon your critical range increases by 1. After 1 minute or if you score a hit in that time, your critical range drops back to normal.
Deadly Strike
Trigger: Any successful natural even attack roll.
You can re-roll all 1s and 2s from your damage dice with this attack. If you have the Great Weapon Fighting Style, you may also reroll any 3s for damage. You must accept rerolled damage rolls.
Florentine
Trigger: Any successful natural even melee attack roll.
You apply the benefits of the Dueling Fighting Style (+2 damage if wielding a melee weapon in one hand and nothing in the other) to this hit. If you already have this fighting style, the damage bonus doubles to +4.
Fortifying Strike
Trigger: A Natural 20.
As a bonus action, you can spend any number of hit dice, as if you had completed a short rest.
Hack and Slash
Trigger: Any natural even melee attack roll.
Repeat the exact same attack against a different target within reach. Damage dealt using this feature is halved. You may not apply the effects of a flexible maneuver to the second attack.
Hold Your Nerve
Trigger: Any natural even roll on a missed attack.
You gain temporary hit points equal to your 1+Constitution modifier (minimum of +1). Does not stack if you have any temporary hit points remaining. Effect lasts for 1 minute.
Hero's Luck
Trigger: Any natural even roll on a missed attack.
Add +1d6 to your attack roll. If you now hit, you deal a glancing blow for half damage (minimum of 1). Damage bonuses due to Strength or Dexterity do not add to this damage.
Intuitive Strike
Trigger: Any natural even hit on an attack roll.
Add your Intelligence modifier to the damage of this attack.
Mark Your Target
Trigger: Any natural even hit on an attack roll.
Until the end of your next turn, any opportunity attack you make against the target struck by this attack has advantage and does not expend your reaction. You still cannot make an opportunity attack if something is preventing you from doing so (e.g. Hold Person spell).
Never Give In
Trigger: Any natural even attack roll.
You can use your reaction to make a saving throw against any temporary effect or condition you are suffering from that can be ended with a save. Alternatively, if other creatures have access to your luck pool (such as through your 18th level class feature), you can allow that ally to make the save.
Pop Free
Trigger: Any natural even hit on a melee attack.
Any time until the end of your next turn, you can take the Disengage action as a bonus action or reaction.
Protective Fighting
Trigger:Any natural even melee attack. You must be using a shield to benefit from this maneuver.
Until the end of your next turn, you gain the benefits of the Protection Fighting Style. If you already have this fighting style, allies within 5 feet of you also benefit from your shield bonus whilst this effect lasts.
Punishing Opportunist
Trigger: Any hit on an opportunity attack with a natural 16 or higher.
The target hit is stunned until the end of your next turn.
Shield Bash
Trigger: Any natural even attack roll with a melee weapon. You must be using a shield to benefit from this maneuver.
As a bonus action, you can make an off-hand attack with your shield, which is considered to have the light property for this attack. If you hit with an even roll on the shield bash, you can also push a target of size Large or smaller 5 feet. You cannot apply another flexible maneuver to this shield attack.
Sighter
Trigger: Any miss with a ranged attack.
Until the end of your next turn, you gain the benefits of the Archery Fighting Style (+2 on attacks with ranged weapons). If you already have this style, the bonus doubles to +4 with ranged weapon attacks.
Remove
Hexblade's Curse. Triggering Roll: Natural 20. You must already be able to cast arcane magic to select this maneuver.
As well as dealing a critical hit and dealing the appropriate damage, if the target lives you can cast the bestow curse spell on the target as a bonus action. Use your arcane spellcasting ability for this feature. This spell is cast at 3rd level, but for every luck point you spend you can cast it at one slot higher.
Hexblade's Foil. Triggering Roll: Natural 1. You must already be able to cast arcane magic to select this maneuver.
You miss your target (possibly to dire consequences), but the intended target of this attack is immediately subject to the bane spell. The spell is 1st level and uses your spellcasting ability that you use for your other arcane spells. This feature may target less than the usual number of targets listed in the bane spell. It only applies to creatures that were the target of your missed attack (up to the spell's maximum).