Middle Sibling - [Lævateinn]

"... When they cast me into this hell, I fell without resistance..."

Through some way or another, you came into possession of the Legendary Blade, Lævateinn, A blade that burns with the fires of the Circles of Hell itself.

Sealed Sword and a Grudge - Level 3

"...Still, I did not lose my smile..."

Lævateinn
You gain a sealed, magic Greatsword. The great sword has a +1 to hit, is considered magical for the purposes of bypassing resistances and immunities, and Deals Bludgeoning damage.
As the battle goes on, you can remove the Seals on the sword. After landing 4 attacks (requirement increasing by 4 each unseal level), you remove 1 seal from the sword. The sword gains the following benefits after unsealing a number of times.
First seal removed (1st unseal): +1d6 fire damage on hit.
Second seal removed (2nd unseal): Bludgeoning damage changed to slashing, +2d6 fire damage on a hit.
Unsealed (3rd unseal): Damage increased to 3d6 slashing damage + 3d6 fire damage, all creatures you choose within a 40 ft. sphere of you take 2d4 fire damage at the start of each of your turns.
The seals magically return to the weapon after combat ends.
At level 7, you start combat in the First Seal Removed state, and the weapon has a +2 to hit instead of a +1.
At level 10, you start combat in the Second Seal Removed state.
At level 15, the weapon has a +3 to hit instead of a +1.
At level 18, you start combat in the Unsealed state.

Check this out!/Grudge
When landing an attack for the first time during your turn, you gain one stack of "Check this!", up to 10 stacks. On a hit with a weapon attack or unarmed strike, you can consume "Check This!" do deal bonus bludgeoning damage equal to twice the expended stacks.
If you land an attack with the first attack you attempted during your turn, you gain 2 stacks instead.
When you spend a total of 5 stacks of "Check this!", increase your progress towards unsealing by 1.

When you or an ally with 40 Feet of you are hit by an attack, you gain 1 "Grudge" stack (Up to 2 times per turn), which can be consumed to use or empower certain features. Grudge has a maximum stack of 10.
When you are hit by 2 attacks in a round, you lose 1 "Check This!" Stack and gain 1 "Grudge" stack.

Enhancement Markings/Rule Violation!!
While you are unarmored, your AC equals (10 + your strength or constitution modifier + half of your proficiency bonus, rounded down). You can also add your proficiency bonus to your unarmed strike damage.

When a creature makes an attack against you and hits, you may make 1 attack against them as a reaction. If the creature misses, you can spend 1 Grudge stack to make 1 attack against them without spending a reaction. You may only spend Grudge using this feature once per round.
At level 10, you may make 2 attacks instead of 1.
At level 18, you may make 3 attacks instead of 1.

Rising Fever - Level 7

"... For the Sword of Legends was mine."

Stomping and Punting
You can spend Grudge to empower your strikes.
Before you make a melee attack, you can choose to spend 1 Grudge to either force the creature to make a DC (8+ Your proficiency bonus + your strength modifier) strength saving throw or take 1d6 bludgeoning damage and be knocked prone, or deal 1d4 additional bludgeoning damage and push the creature back 10 feet.
On a natural 1 on the Saving throw, the creature is stuck in the ground, being unable to stand up for 1 round. If the ground is not solid, like the 2nd floor of a building, the creature breaks through the floor, taking +1d6 fall damage.

Stamp of Vengeance
Once per round, when you use Rule Violation!! while at 10 Grudge stacks, you may spend 5 Grudge stacks to immediately make two additional unarmed strikes against the attacker. These attacks deal an additional 1d4 bludgeoning damage on hit.
This feature only counts for 1 hit towards unsealing Lævateinn.

Don't let a little thing like this Break You! - Level 10

"Oh yeah, I'm down to unbox a layer of packaging for this fight!"

Discard Packaging
When you remove a seal from Lævateinn, you may immediately make one ranged weapon attack as part of the same attack that removed the seal (10/40 feet range, 1 target, 1d6 Bludgeoning damage + [# of seals removed]d6 fire damage), as you lob the seal at the target.
If you have fully unsealed Lævateinn, your unarmed strikes deal an additional 1d6 fire damage, and you take 2 less damage from attacks.

Book of Vengeance - House of [_______] Special Clause
At the end of your turn, the creature that has landed the most hits on you or your allies gains "Book of Vengeance". When you hit a creature with "Book of Vengeance", or an ally hits a creature with "Book of Vengeance" using an unarmed strike or with an attack that deals Bludgeoning damage, an additional 1d6 Bludgeoning damage is dealt.
All of Your attacks benefit from Book of Vengeance, regardless of the damage type.
Only one creature can have Book of Vengeance at a time, if the creature with Book of Vengeance dies, all allies that have damaged the creature gain 3d6 temporary hit points.

I'll gut you like a fish! - Level 15

"Be warned, it's gonna be hot, Hot as hell!"

Inferno [Lævateinn]
When Lævateinn is fully unsealed, after making an attack using it (hit or miss), all creatures you choose within 15 feet of you must make a constitution check (DC = 8 + your strength modifier + half of your current Grudge, rounded down), taking 2d4 fire damage on a failure. Each creature can only be affected by this feature once per turn.

Ridiculous Grit
When you fully unseal Lævateinn, until the end of your next turn, all damage you take that is above 5 is reduced to 5 (after damage reduction from 'Discard Packaging'). After this effect expires, you gain "Ridiculous Grit" until the end of combat. While you have "Ridiculous Grit", Reduce the damage you take by your proficiency bonus (cannot be reduced below 0), and deal additional damage equal to the number of attacks that hit you during the previous round.
Once per long rest, when damage would reduce you to 0 hit points, you instead take no damage from that source and regain hit points equal to twice your Fighter level.

"Your Sacrifice Won't be Forgotten..." - Level 18

"Remember, Kiddo? We're family. A little sacrifice ain't a thing between us!"

Good [____]... Your Sacrifice for the Family Won't Be Forgotten.
While Lævateinn is fully unsealed, when an ally within 60 Feet of you is hit by an attack, and the damage would reduce them to 0 HP or below, you can use your reaction to cancel the attack and immediately move within 5 feet of an ally and make an attack with Lævateinn, targeting both the triggering creature and the ally. The attack automatically hits and is considered a critical hit. The damage from this attack cannot reduce the Ally's Health below 0, and if the ally is downed by the attack, they become stable, and you Gain "Avenging my Family" until combat ends.
While you have Avenging my Family, you gain a +2 to hit with attacks from Lævateinn, and you deal an additional 2d6 fire damage with all attacks.

Any failed death saving throws the sacrificed ally has accumulated are removed.


Complete and Total Extermination!!! [Lævateinn]
While Lævateinn is fully unsealed, while you have a total of 10 ('Check This!' stacks + 'Grudge' stacks), you can use a special attack:

Complete and Total Extermination [Lævateinn];
Make a weapon attack against a creature using Lævateinn, the attack has an additional +2 to hit, and cannot suffer the effects of a critical failure. On a hit, expend all 'Check This!' Stacks and 'Grudge' stacks to deal (Grudge stacks expended)d6 Slashing damage + (Check This! stacks expended)d6 fire damage.
You can only use this feature up to 2 times per combat encounter.