"The Way of the Asura 修罗之道 (xiū luó zhī dào)"
(Asuras are mythical Demi-Gods in Buddhist mythology that are wrathful, prideful, arrogant, and love to fight. Click here for Asuras Wiki.)
Why is he a Demi-God:
Let's list out a couple adjectives to describe Lu Bu -
1. Arrogant (Striking his halberd with an arrow to win a truce between Yuan Shu 袁术 and Liu Bei 刘备)
2. Wrathful (Killing Dong Zhuo 董卓 over Diao Chan 貂蝉)
3. Loves to fight (1 vs 3 against the sworn-brothers-three)
4. Prideful (Loves to hear compliments and receive gifts that stroke his ego).
... and lastly...
5. Not very bright (no relation to the Asuras)
Notice that the description is quite accurate about him, placing his personality amongst the Asuras. Perhaps that is why he is a Demi-God: because the Asuras are Demi-Gods themselves. Therefore this Demi-God character has nothing to do with his death, but everything to do with his actions while he was alive.
Character ability 1: [Enforced ability] "Violent Rage 狂暴 (kuáng bào)"
At the beginning of the game, you get 2 "Rage 暴怒" tokens. Every 1 unit of damage you cause or suffer, you receive 1 Rage token.
Character ability 2: [Enforced ability] "Simpleton 无谋 (wú móu)"
Every time you use a tool card (with the exception of Time-delay Tool Cards), you must discard 1 Rage token or lose 1 unit of health.
Character ability 3: "Unprecedented 无前 (wú qián)"
During your action phase, you can discard 2 Rage tokens and select 1 target player. For the rest of your turn, the target player's Armour becomes ineffective. In addition, you acquires Lu Bu's "Without Equal 无双" ability.
Character ability 4: "Asura's Fury 神愤 (shén fèn)"
During your action phase, you can discard 6 Rage tokens. Every player (except yourself) will:
(Carried out in order from 1 to 3)
1. Receive 1 unit of damage
2. Discard all equipped cards
3. Discard 4 on-hand cards
After this is done, you must flip your character card. Limited to once per turn.
Ability's relation to story:
Abilities 1, 3 and 4 are created for this character with little to no link to the story. "Simpleton" has some links to the story, but I need not elaborate here as it has been described in my previous post on (normal) Lu Bu.