- mission from Halo 2
This is one of the more difficult missions in the game, simply because the sheer number of enemies can overwhelm you if you do not contain them.
In this mission you start off on yet another moving barge. When the barge reaches its end there will be several swarms of Flood creatures that attack you in waves. This is one of the more challenging stages and you will have to try to bottleneck the Flood.
They enter through a tube on the lowest level of the barge - kill the first wave of the flood then go to the lower level and look for the tube. When you've found the tube, move back up a bit so that you have a view of the area where the Flood will come out. This is your "Killing Area", where you will make sure the Flood cannot swarm the entire ship, otherwise they will overwhelm your allies and you.
The key here is to control them right at this entry point. The position you should be taking is slightly above the lower area where they enter, from there you can shoot them and also lob grenades into the lower area. As the Flood enter that area some tend to stand there a second or two, this is PERFECT opportunity to take them out with grenades. Make generous use of grenades, literally throwing them into the pit or into the tube itself every opportunity you get. If done correctly, you will kill them off as them come out and not give them a chance to swarm. If any escape your barrage of grenades use an Energy Sword to finish them off, but QUICKLY return to your original. Every so often, run down to the killing area to pick up additional grenades.
Using this strategy you should be able to kill off all the swarms of invaders with grenades and still be left with enough to continue your mission.
Be wary however, and note that Flood will attack until the mission is literally over and the barge stops moving completely (there are several stages where the barge is moving, so do not relax until your allies tell you to go retrieve the Sacred Icon. When all Flood are dead, the mission is ended, and next begins That Old, Familiar Feeling