Three grenade types:
To start off, there are 3 types of grenades. They are also considered to be "equipment" items in the game. Two of them act just like a grenade, toss and explosion effect. The hologram is a bit different, as it will place a decoy in your location when used. Via the Praetor tokens and on the Praetor menu screen, the player can upgrade their equipment module. I suggest doing this early because equipment items can save your life in this game. You can increase the amount of charges for your equipment up to 2. The player can also increase its effectiveness in battle and finally lower cool down times.
Frag Grenades:
These are your basic grenades and you should acquire them first in Mission #1 the UAC. They are the most powerful, impacting weapon of the 3. However this does not mean they are the most useful, each and every equipment piece has it's advantages. The frag grenade explodes in a nice radius and can damage all and any enemy at any time unless it is shielded by a force barrier or something similar.
Siphon Grenades:
These are the last of the grenades you will acquire. I find they are the coolest looking and very very practical to use. You will get them in a later game mission in the game's Hell area. They also look great on the menu screen and even the HUD (Heads up Display). The codex for them really explains how well they can work in game and it's an interesting read.
Check out the video below for them in action:
Holograms:
You can acquire the Holograms at the end of the Argent Tower level/mission. Soon after they will be found in several other places in the game. They are actually quite the distraction. If timed right all enemies will attack it and continue to do so until the decoys time span runs out.
However it should really be used as an evasive tactic. This is because once you begin firing again and a demon notices you, you will enrage the demon making it set sights on the Doom Marine (You). So in a nutshell use these when health is low and your looking for an escape route to a nice piece of armor or more health/ammunition.
Honestly I love them all. I love the icons for each, the codex and the tactical advantages for each one. Also it's nice to upgrade them via the Praetor suit tokens. Maybe one gripe is they could have added more of these equipment type items? Perhaps an ice grenade or just a plain fire grenade. We will see when the games DLC comes out.
