The Ghost Strategist

During the Three Kingdoms era, there was a strategist whose words always came true. No matter which lord he served, he managed to thrive. He killed his lord's eldest son, nephew, and trusted general, yet still rose through the ranks under that same lord. Among the top strategists of the Three Kingdoms, he was the only one to live past seventy and die peacefully in his bed. The history books have little to say about him, and later generations have argued fiercely over his legacy. What kind of extraordinary life did he lead? Let's find out from the perspective of someone who transmigrated into that era.