Warcraft 3 Frozen Throne Walkthrough for Night Elf Sentinels:
Chapter 8: The Brothers Stormrage
Main Quest: Tyrande's Rescue
Use Illidan's forces to destroy the Red Undead baseOptional Quest: Dam Trolls
When you first start this chapter, which is the final mission for the sentinels in Warcraft 3, you'll have two bases. One for Illidan and one for Malfurion. Illidan's base needs to prepare for an assault, while Malfurion's just needs to outlast the enemies' attacks. Hotkey Malfurion's army to group four. You want to build your way toward having a full group there. Attacks at Illidan's base will come from the northwest near the goblin merchant, so build an extra tidal guardian or two there to protect your base. Malfurion could use a couple extra ancient protectors at the northeastern and southern sides of his base. Most importantly, you need to watch for when they are being attacked and use all your forces to defend the base while malfurion surrounds them with tranquility.
Illidan's Naga base should start with four myrmidons. You will want the two sirens in his group to be set on frost armor, while you put the dragon turtle in a second group. Make Illidan's army be full of Myrmidons and the two sirens. When you have your full group with Illidan, head south to fight a group of gnolls by the river to the east that will drop a ring of protection +5, a nice defensive boost for Illidan. Back at your base, make three more dragon turtles.
Once you've got the ring for Illidan, head south along the river and there will be a small cutscene indicating you can kill the river trolls to reveal a shortcut. Do so, for they drop a nice item for Illidan anyway. There are several groups of trolls to be fought. The first ones don't drop anything, but must be cleared to reach the final troll which will drop a mask of death which will allow Illidan to heal when he attacks enemies.
The next step should be to build a pair of coral beds to raise the Naga's population cap to 100. You want your final composition to look like:
Use these forces to assault the Elder Sasquatch and his group. Keep them all together so that you don't have as many losses. This will not only get you a crown of kings +6 (adds to strength, intelligence and agility), but provide access to a fountain of health and a ramp that leads to a small undead base that needs to be tackled before the red.
Once the Sasquatches are down, you should be free to assault the Undead base west of the fountain. Reinforce your army before you do this if you took any losses. Send the myrmidons in first followed by everyone else and focus on spirit towers with your dragon turtles. Once this base is down, it's a straight shot to the north to the red base. If you aren't good at micromanagement, you could take the time to build a few tidal guardians then draw the majority of the red base into their line of fire. I recommend this as it makes the last fight so much easier, and doesn't take that long to throw together.
If you don't build the tidal guardians, things will be a bit harder. Use your myrmidons to net the dragons and devour abominations or crypt fiends with your dragon turtles. Focus fire the sirens and snap dragons as much as you can, and by all means transform Illidan and use mana burn liberally.