Originally Posted by
Qualia
? You may want to play WC3 again, and read up on "Rise of the Lich King" while at it. Arthas wasn't weakened when he fought Illidan, LK already restored his power. In fact, Lich King empowered Arthas with all he could afford back then, making Arthas even more powerful than he ever was before that. Arthas was lvl 10 on my last mission, so I'm sure you're just misremembering it :P Or, if we go with the more canon depiction of the event, the novel stated that "Coldness suddenly began to seep through Arthas, numbing the angry, raw pain, calming his thoughts. The energy was so vast, so heady…it was more powerful even than what Arthas had known before. This, then, was why he had come. To drink deep of this icy draft, to take the cold strength of the Lich King into himself".
And while we are at it, "Rise of the Lich King" also described how the fight actually went in details: it was an even fight, and Illidan actually had upperhands at times. He received a slash on his torso, but pushed Arthas back on his knees and bathed him in Fel fire powerful enough to knock the DK down. Arthas only managed to get the final - albeit most important - hit in when Illidan came to personally deliver the finishing blow. Arthas triumphed, but just like how Grom won against Mannoroth, it wasn't direct result of him being the more powerful fighter - if Illidan wasn't arrogant, Arthas would have been done right there. This isn't even pre-TBC / Legion Illidan, for that matter.
And no, Grom didn't take Cenarius 1v1, unless I'm missing something big from one of the novels. In game, he fought against Cenarius with his Chaos Orc / Orc drank Mannoroth blood. In regards to Mannoroth, Grom only managed to kill him because of Fel Blood + surprise strike when Mannoroth underestimated him during WC3, or surprise strike + Iron Star in AU Draenor before WoD. Red Grom is powerful, but not as powerful as Mannoroth normally.
Just make something straight, because without PiS, Mannoroth would wipe out Grom and Varian. Probably both at the same time.