The vanguard class is one of the most exciting Mass Effect 2 classes available in the game. Here's an overview of what abilities to focus on if you choose to play this class.
1. Shockwave
This biotic ability sends out a massive blast of energy at your enemies. Shockwave works against one or multiple opponents sand knocks them back, giving you time to follow up with a round of fire or melee attacks if you're close enough. Shockwave can be improved to knock down even more opponents as you level up in the game.
One of the coolest features of the vanguard, shockwave is definitely an ability you want to improve if you play a vanguard in Mass Effect 2.
2. Charge
Perhaps the signature ability of this class int he game, the vanguard's charge ability is exciting and fun, bringing you quickly into melee range of all your enemies. The animation for this thing is really neat just on its own. Basically, charge lets you quickly get into melee so you can fire or hit your opponents til they're dead.
Charge is great if you like rushing your enemies. Definitely something you want to upgrade as you go through the game, as well as shockwave.
3. Additional addon abilities
You can get things like neural shock, reave, geth shield boost, and other "addon" abilities as you progress through the game. Depending on your personal playstyle, you can get different addon abilities that will let you enhance your style of fighting. If you're more defense oriented or you're suffering from survivability issues, getting the geth shield boost or an enhanced shield ability will help you stay up longer.
Ultimately the vanguard class is great for people who like to be up close and personal with their enemies. If you're not so crazy about this style of play however, you should try the soldier or infilitrator classes which are based more around killing from a distance.
The vanguard is the most offensive and melee oriented of all the classes in Mass Effect 2. While you do receive biotics abilities, you won't be able to use a sniper rifle with this class, which is something to ear in mind if you're fond of sniping.
In addition, your engineering abilities are limited with the vanguard class. You don't get access to a lot of the engineer’s nifty synthetics boosters, or the ability to reprogram the AI of certain types of mobs in the game.
In addition, your healing abilities will be limited with the vanguard. It's more of a gladiator style class than anything. There won't be a lot of support capability if you choose to play a vanguard, so exp ect to be at the front lines - and often, right in your enemies' faces.