This build makes pantheon very devastating and sustainable. The reason i rush manamune is for pantheons poke. He can use his combos and not worry about being out of mana. Build mercury's treads next. its really good because of the tenacity and the resistance. Build a frozen heart next. it will give you more attack power cause of the manamune and more sustain from the armor. it also gives you cooldown reduction which is excellent for pantheons combo. After the frozen heart, pick up a brutalizer. It will give you damage, cooldown, and armor penetration. After this, pick up a frozen mallet, you could also build a warmogs instead given the situation. after build an atmas! Atmas is good because it gives you more armor and about 40 damage. if you are going up against more tanky champs build a last whisperer rather than atmas. armor pen is very good.