Okay so I’ve been going through the campaign over the last three days and I got to The Halo mission. I accidentally played through on normal first and thought it was really difficult and I thought it was legendary. Nope. I went back to try it on Legendary and I can’t even get past the Banished and Retriever sentinel attacking my base. It is impossible to build enough units to destroy the sentinel in such short time plus fight the Banished. Not to mention the constant plasma bombardment leader power. I’ve tried many times to beat it but it’s impossible. Any one know what to do?
Build Scorpions only. Put your Spartans inside them always. Drop ODST units near control points to cap them if needed. Also have your Scorpions 50/50 on the control point next to your base and on the control point at the top-middle of the map. You only need two in control to win and you won’t anyways have resources to defend all three.
Avoid the Retriever Sentinel: you don’t have to kill it. It stays on the left and middle sides of the map. It doesn’t go to the right side or near your home base. You can hold your units at the nearest control point in place all the time. When the Retriever Sentinel comes near your units on the top-middle control point, move your units away to the right or upward and right. After the Retriever Sentinel turns to another direction and floats away, you can return your units to the top-middle control point. During this movement, there are often Banished units attacking this control point. Hence the Scorpions + ODST drops + Bombs + Turrets.
After I used this strategy I was able to beat this mission on solo legendary relatively easily.
Tommi theKrogan thanks for the advice. My main issue was the sentinel in the beginning. I didn’t have the forces to take it out and it always killed my base. I managed to get the aggrieved off my units and let it sit where it spawned and I had unlimited time to prepare. I then did as you said and built ODST and Scorpion. Your strategy worked well thanks.