We all have our little hates about the Flood, but there is a simple way of stopping it! I'm going to run through 6 of my top Flood Fighting Tricks:
6) Carrier forms are walking bombs. Kill a nearby combat form, then throw a grenade. If your lucky, the grenade will touch off any the combat form was carrying, taking the whole lot shy-high.
5) Don't use the sword or grenades on dead combat forms! Make sure you clear an area first, then go round hitting the bodies with a heavy weapon (usually a plasma rifle, battle rifle, shotgun etc). If you hear a snap or a gristly sound, then your on the right track! If you hit them enough times, they will explode, just like being hit with the sword!
4) Rapid fire weapons duel wielded tend to make a mess of that nasty combat form close up, but usually don't have the punch to nail it in one go, and by the time it drops theres 2 more to replace it. Try to get a couple of Magnums as a fall back weapon, because they pack the punch needed to drop it in a few shots.
3) Scorpions and Wraiths. Who doesn't love a big HE shell being lobbed at the opponent? The Flood tend not to take to kindly to you doing it though, so watch out for tank-jacking combat forms.
2) Your shields can usually take a few hits from infection forms, so instead of shooting them on sight (they can move to fast for some people), throw a grenade just in front of the cluster, then let the survivors latch on. Just keep an eye on those shields!
1) Sometimes the best way to kill them is to wait and let other enemies kill them first! Its easier to kill 4 or 5 Flood forms, instead of 10 or more and some Covenant/Sentinels as well.