context: Generals Miki and Washizu are Samurai commanders under a local lord, Lord Tsuzuki, who reigns in the castle of the Spider's Web Forest. After defeating the lord's enemies in battle, they return to Tsuzuki's castle. On their way through the thick forest surrounding the castle, they meet a spirit, who foretells their future. The spirit tells them that today Washizu will be named Lord of the Northern Garrison and Miki will now be commander of the first fortress. She then foretells that Washizu will eventually become Lord of Spiderweb Castle, and finally she tells Miki that his son will also become lord of the castle.
  When the two return to Tsuzuki's estate, he rewards them with exactly what the spirit had predicted. As Washizu discusses this with Asaji, his wife, she manipulates him into making the second part of the prophecy come true by killing Tsuzuki when he visits. Washizu kills him with the help of his wife, who gives drugged sake to the lord's guards, causing them to fall asleep. When Washizu returns in shock at his deed, Asaji grabs the bloody spear and puts it in the hands of one of the three unconscious guards. She then yells "murder" through the courtyard, and Washizu slays the guard before he has a chance to plead his innocence.
  Tsuzuki's vengeful son Kunimaru and an advisor to Tsuzuki (and rival of Washizu) named Noriyasu both suspect Washizu as the murderous traitor and try to warn Miki, who refuses to believe what they are saying about his friend. Washizu, though, is unsure of Miki's loyalty, but he wants to trust his friend and he still plans to let Miki's son be his heir, since he and Asaji have been unable to bear a child of their own.
  Washizu plans to tell Miki and his son about his decision at a grand banquet, but Asaji tells him that she is pregnant, which leaves him with a quandary concerning his heir, as now Miki's son has to be eliminated. During the banquet Washizu drinks sake copiously because he is clearly agitated, and at the sudden appearance of Miki's ghost, begins losing control. In his delusional panic, he reveals his betrayal to all by exclaiming that he is willing to slay Miki for a second time, going so far as unsheathing his sword and striking over Miki's mat. Asaji, attempting to pick up the pieces of Washizu's blunder, tells the guests that he is drunk and that they must retire for the evening. Then one of his men arrives with the severed head of Miki. The guard also tells them that Miki's son escaped.
  Later, distraught upon hearing of his wife's miscarriage and in dire need of help with the impending battle with his foes, he returns to the forest to summon the spirit. She tells him that he will not be defeated unless the very trees of Spider's Web forest rise against the castle. Washizu believes this is impossible and is confident of his victory. Washizu knows he must kill all his enemies, so he tells his troops of the last prophecy, and they share his confidence. Night falls at the castle and the guards hear wood being cut down. Maybe they're building fences? It's too dark for them to see. Over in Washizu's chambers, the Lord of Spiderweb Castle and his men wait for an attack. Suddenly birds fly into the castle, but Washizu laughs and tells them it's a good omen, insisting that they wait.
  The next morning, Washizu is awakened by the screams of attendants. Striding into his wife's quarters, he finds Asaji in a semi-catatonic state, trying to wash clean the imaginary foul stench of blood from her hands, obviously distraught at her grave misdeeds. Distracted by the sound of his troops moving outside the room, he investigates and is told by a panicked soldier that the trees of Spider's Web forest "have risen to attack us." The prophecy has come true and Washizu is doomed.
  As Washizu tries to get his troops to attack, they remain still. Finally they turn on their master and begin firing arrows at him to appease Miki's son and Noriyasu. Washizu finally succumbs to his wounds just as his enemies approach the castle gates. It is revealed that the attacking force is using trees cut down during the previous night to disguise and protect themselves in their advance on the castle.
question: How does Asaji help Washizu kill his lord?
answer: gives drugged sake