Whenever a Zealot wielding an energy sword approaches, he will pause, scream, and shake around before he attacks. That's the best time to stick him with a plasma grenade.
The plasma grenade also works against Promethean Knights, especially as they spawn or teleport in. This effect is minimized in Halo 5: Guardians, though, due to their new armor system.
When you throw two or more plasma grenades into one tight-knit area, the first grenade's explosion can cause the other grenade to launch in any direction then detonate. Use this skillfully to take down an enemy's shield or score a lucky kill.
Elites will dive away from grenades, even when on bridges or high ledges (such as the canyon bridges in Halo: CE's Assault On The Control Room), allowing a cunning player to make them effectivly commit suicide. Grunts will run toward their companions when a plasma grenade is stuck to them. This is effective at maximizing casualties against the Grunts' commander.
Whereas the frag grenade will explode roughly one second after coming to rest, the plasma grenade takes about three seconds. The grenade's bounce is considerably less than the frag grenade's, as well. Keep this in mind when timing your throws so your target can't rush past the grenade.
Some high ranking Covenant commanders cannot be stuck, such as Brute Chieftains, as their armor cannot be stuck by Plasma and Spike Grenades. However, their weapon can still be stuck, which usually results in an immediate kill. Once their helmet is knocked off, you can stick a plasma grenade to the exposed area of the Brute.
Like all grenades, it can be shot by a precision weapon to cause immediate detonation. This can be an effective trap if you can successfully bait your enemy.
If you stick an Elite or a Brute they will either charge you in an attempt to take you out, or take cover to protect their allies. Sometimes, if an Elite is stuck on the chest in Halo: CE, he may flail his arms in an attempt to take off the grenade then begin to run away and scream.
By making an enemy Grunt stagger or shift while throwing a Plasma Grenade it can cause the Grunt to stick his comrades by accident, due to Grunt standard operating procedure of fighting in groups. This increases the possibility of the grenade killing the thrower, if not his comrades. Another way of using this tactic to your advantage is to injure the Grunt right as he throws the grenade. This will cause him to drop it on the ground and get killed by the explosion. This also works with suicide Grunts; if you can kill them just as they start charging, the two grenades they drop will detonate and kill any surrounding allies.
Dropped plasma grenades will often cause chain explosions with other grenades that are nearby when fired upon as long as you use explosive weapons. The only exceptions are grenades that are not dropped from a killed enemy.
In Halo 5: Guardians, the plasma grenade originally could not instantly kill campaign playable characters and make them unrevivable even when it stuck to them. It has since been updated to instantly kill a character and make them unrevivable should it stick to them.
The Plasma Grenade is one of the most helpful grenades in the game. It is advised to not waste it on a weak or unimportant target. It is recommended to use it against vehicles, as its blast can flip a Mongoose or Ghost, and a successful stick will often leave the vehicle mostly unharmed but empty.
In Halo 3, the Plasma Grenade can be slammed away by the effects of a Gravity Hammer, but the force of the hammer may cause grenades to detonate immediately. This makes this tactic risky.
Players have been known to somehow "remove the sticky" and throw it back, but on closer inspection you will notice that it only works if you stick your hand, then throw a grenade or a piece of Equipment.
In some cases a player can throw a Plasma Grenade onto a Power Drain and let it roll inside a Bubble Shield. The Plasma Grenade will pass inside the shield and detonate killing anyone unaware of what has happened.
In a Forge game, after getting stuck as a Sangheili/Spartan, turning into monitor mode will cause the grenade to not detonate. But if you turn back into Sangheili/Spartan, the grenade will explode and can serve as an effective suicide bomb.
If you see a team of two near each other, throwing a Plasma Grenade on one Spartan can wipe out the other man, since the Plasma Grenade has a wide blast radius.
If a player's weapon is stuck with a Plasma Grenade, it is possible to pick up another weapon, thereby dropping the "stuck" weapon, and live. The Plasma Grenade will stay on the dropped weapon and still explode, though not be considered a stick. Switching for your secondary weapon won't help, since you still carry the "stuck" weapon.
This works in reverse as well; sticking a weapon that an enemy will then pick up is an effective way to deny them that weapon. This works especially well in chaotic Rumble Pit or Multi Team matches
An effective tactic to deal with Ghosts is to bait the driver into attempting to run you down (the prefered tactic for most Ghost operators since it is much faster than shooting with the vehicles cannons), leap as they boost towards you, and stick the hood. If you're lucky, the grenade will kill the driver, leaving the Ghost for your use.
The Plasma Pistol and Plasma Grenades are a lethally effective anti-vehicle combination in Halo 4. It is rare to play a Heavies or Big Team Battle game without seeing at least one player using this combination.