The troops the Night Elves brought to garrison Ashenvale and Felwood Forest, while certainly elites from all aspects such as Sentinels, Druids, and Priestesses of the Moon, were definitely not the Night Elves' entire strength.
They had lived in these forests and mountains for nearly ten thousand years, and apart from the War of the Shifting Sands a few millennia ago, and the Satyr War even further back, the Elves had ample time to recover.
Especially now, they were still sheltered by Nordrassil's shade, and although the Elves no longer used the Well of Eternity, the power of this well flowed continuously into this "Crown of the Heavens" through Nordrassil's roots.
So, while the Well of Eternity appeared to be "obscured" and "sealed" by Nordrassil, in reality, the well was still continuously providing aid to the Elves.
Therefore, for whatever reason, the Night Elves would certainly strictly guard the area around the well, and the Night Elves' grand army was originally supposed to be the last line of defense on Mount Hyjal, fighting against The Polluter.
However, with the experience of successfully "constructing" defensive fortifications on Mount Hyjal, achieving this was not entirely impossible.
The method was also very simple: make the Night Elves fully realize the danger of this situation, no longer hold back in allying with the Alliance, but truly open up and allow themselves to set up defenses on Mount Hyjal in advance.
Looking at it now, a single Pit Lord, Mannoroth, was still completely insufficient, as this fellow was not an unbeatable opponent for a planet like Azeroth, which had nurtured various magical civilizations.
He could not achieve a crushing posture against the Elves; even with a large wave of Demon armies, it would only go from difficult to deal with to relatively difficult to deal with.
In ancient times, the one who single-handedly held back Mannoroth was none other than the Great Druid Malfurion's brother, the man regarded as a traitor and monster by the Night Elves.
Arthas was unsure of this "betrayer's" strength, but since he could contend with Mannoroth ten thousand years ago, and after ten thousand years imprisoned in a dungeon, his strength unable to increase, he was still evenly matched in his later fight against "himself," indicating that Mannoroth's strength was at most a relatively high level among demigods.
Therefore, since Grommash could cleave Cenarius, he could cleave Mannoroth; this was beyond doubt. The orcs' tricky opponents should actually be the Demon armies in that canyon.
It would be difficult for Thrall and his orcs to face the Pit Lord himself without paying a price.
Mannoroth was regarded by the Night Elves as a controllable danger, while Tichondrius represented a completely unpredictable danger.
Tichondrius's strength might not be as great as Mannoroth's, but compared to the Pit Lord, who preferred direct crushing and destruction, his danger was even higher.
Arthas did not know what this fellow was doing now, but it was probably nothing good, which was why he had Malfurion return to Felwood Forest to inspect first.
If they fought the Demons in Ashenvale and their backyard caught fire, the consequences would be unimaginable.
Arthas did not care if Felwood Forest was in danger, or how great the danger was; those were problems that had already occurred or were about to occur. He needed accurate intelligence to allow him to respond in a timely manner.
The Elves were arrogant and foolish, wanting to quickly resolve the conflict with the Burning Legion's vanguard. Arthas did not need to bring the Alliance's living forces to play along with the Elves; these were the forces they had accumulated over more than ten years and could not be given away for nothing.
So, the current choices were actually two: first, thoroughly eliminate all Demons on Azeroth, fundamentally solving the problem of Archimonde's immediate arrival; second, make defensive preparations in advance along the Burning Legion's inevitable path, to avoid a collapse at the first touch.
The route goes without saying; the Burning Legion, coveting the power of the World Tree and the Well of Eternity, and needing to set up portals for subsequent troops, would only take that single path to ascend Mount Hyjal. Moreover, constrained by the current situation, after summoning Archimonde, the Demons should have no remaining strength to summon additional Legion cannon fodder.
Furthermore, finding an excuse to enter Mount Hyjal actually had other reasons.
Arthas indeed had a very clear purpose for the power of the Well of Eternity.
The Elves possessed such a source of magic, and in just a few thousand years, they completed racial optimization and created an extremely prosperous civilization.
After all, having an inexhaustible source of energy nearby makes many things extremely convenient.
He just did not want to move the Well of Eternity back to the Human Kingdom, because even if human civilization developed rapidly, at the same time, decay and corruption would breed among the populace. To put it plainly, for intelligent beings to possess such a source of energy was a veritable double-edged sword; the benefit was rapid civilizational development, but the people would also lose their caution against crisis.
Looking at it now, compared to Humans, those "mindless" Undead were more suitable for using this magical power.
If he could obtain some spring water with the characteristics of the Well of Eternity and transplant it into the Scourge's headquarters, it should allow the Undead Scourge's power to grow rapidly without relying on slaughter.
The original Scourge had devoured the resources and population of almost half of the Lordaeron continent, and even defiled the Sunwell, the holy land of the Elven Kingdom of Quel'Thalas, plundering a large amount of treasures and magical knowledge, only then managing to rapidly develop and grow in Northrend.
Arthas's Scourge naturally could not follow this old path, so it was inevitable that the Undead's strength would grow too slowly. Previously, he could only choose to resurrect some heroes and powerful individuals who were gradually forgotten by people.
If this continued, although the existing Undead were also a very powerful force, using them to fight the Burning Legion and the Old Gods would be somewhat of a pipe dream.
Therefore, finding a way to secretly take this power and study it well in his own domain now also seemed like an excellent opportunity. However, the newly regenerated Well of Eternity no longer possessed the ability to assimilate similar lakes, so Arthas had to find Malfurion's brother; he possessed the true Well of Eternity water preserved from ancient times.
Thinking of this "betrayer," Arthas suddenly had a two-birds-with-one-stone idea—no, it should be three birds with one stone.
He now needed someone who would both trouble the Elves and give the Demons no advantage. This person was naturally the man who had been imprisoned in a dungeon for ten thousand years, regarded as a betrayer by his own people. His escape would cause the Night Elves to be preoccupied while bringing immense pressure to the Legion's Demons.
Because he was the man known as the Demon Hunter.
Illidan Stormrage!