Runeblade

RUNEBLADE

Unique Greatsword, requires attunement (does not count as a rune for the purposes of Rune Mastery)

The Runeblade is a Sentient item with WIS 18, INT 18 and CHA 10. It can speak telepathically to the person currently attuned to it as long as they are within five feet of each other, and can use the senses of the person currently attuned to it as though they were its own. If it is stored in an extra-dimensional area granted by a class, such as a Blade Pact Warlock's Pact feature, or bonded to the wielder in some way, such as a Eldritch Knight's Weapon Bond, it is treated as always being within five feet of the wielder. It has proficiency in the History and Arcana skills, and will refuse to talk to anyone who cannot provide it with an interesting conversation in regards to these subjects (read: has proficiency in those skills) It is Lawful Neutral, and desires to teach its weilder about the nature of runic magic. In doing so, it affects the mannerisms of an ancient master.

*Sleeping (no prerequesites)
Whilst sleeping, the Runeblade is nothing more than a regular Greatsword that requires attunement. It does not deal magical damage and does not grant any other bonuses.

*Dozing (requires one rune to be known by the weilder, requires some co-operation between blade and wielder)
Whilst dozing, the Runeblade counts as whichever Rune the wielder knows. In addition, any damage dealt by it counts as magical damage. Furthermore, the sword gets a permanent stacking +2 to INT and WIS.

*Roused (requires two runes to be known by the weilder, requires constant co-operation between blade and wielder, requires 3rd level)
Whilst roused, the Runeblade counts as one of the Runes the wielder knows, switchable as a bonus action by the wielder. In addition, any damage dealt by it counts as magical damage, and it gains a +1 to damage and attack rolls. Furthermore, the sword gets a permanent stacking +2 to INT, WIS and CHA.

*Awoken (requires three runes to be known by the weilder, requires allegiance between blade and wielder, requires 8th level and at least one level in the Rune Master prestige class)
Whilst roused, the Runeblade counts as one of the Runes the wielder knows, switchable as a bonus action by the wielder. In addition, any damage dealt by it counts as magical damage, and it gains a +2 to damage and attack rolls. Furthermore, the sword gets a permanent stacking +2 to INT, WIS and CHA.

*Empowered (requires four runes to be known by the weilder, requires friendship between blade and wielder, requires 13th level and at least two levels in the Rune Master prestige class)
Whilst roused, the Runeblade counts as one of the Runes the wielder knows, switchable as a bonus action by the blade. It also allows constant access to the Simple properties of any rune currently known by the wielder. In addition, any damage dealt by it counts as magical damage, and it gains a +3 to damage and attack rolls. Furthermore, the sword gets a permanent stacking +2 to INT, WIS and CHA.

*Unleashed (requires five runes to be known by the weilder, requires near-perfect trust between blade and wielder, requires 18th level and at least three levels in the Rune Master prestige class)
Whilst roused, the Runeblade counts as one of the Runes the wielder knows, switchable as a bonus action by the blade. It also allows constant access to the Simple properties of any rune currently known by the wielder. In addition, any damage dealt by it counts as magical damage, and it gains a +3 to damage and attack rolls. In addition, the Runeblade gains the benefit of the elemental bonuses associated with the rune it is currently attuned to. Furthermore, the sword gets a permanent stacking +2 to INT, WIS and CHA.

*Apotheosis (requires six runes to be known by the weilder, requires perfect trust between blade and wielder, requires 20th level and at least five levels in the Rune Master prestige class) [At this level, the Runeblade is a potentially divine-level artifact]
Whilst roused, the Runeblade counts as all of the Runes the wielder knows. It also allows constant access to the Simple properties of any rune currently known by the wielder. In addition, any damage dealt by it counts as magical damage, and it gains a +3 to damage and attack rolls. In addition, the Runeblade gains the benefit of the elemental bonuses associated with all runes the user is currently attuned to, though the bonus damage is only gained once, chosen and changed as a bonus action. Furthermore, the sword gets a permanent stacking +2 to INT, WIS and CHA, and it gains two major beneficial artifact properties, two minor beneficial properties, one minor detrimental properties and one major detrimental property.

All bonus damage is equal to the damage the weapon deals
FIRE: Fire damage
COLD: Cold damage, forces a DC 16 DEX save on hit versus half movement until the end of the target's next turn
EARTH: Bludgeoning damage
AIR: Slashing damage, gains the Reach property
WOOD: Poison damage, applies the poisoned condition. If the target is already poisoned, forces a DC 16 CON save on hit versus Stunned
METAL: Slashing damage, critically hits on a 19-20
HEAVEN: Radiant damage
VOID: Force damage