Warframe has a robust melee system, but heavy melee attack is often misunderstood and ignored. It's a shame, because it can have an incredibly powerful impact against enemies, and will absolutely melt away most of the toughest challenges in the game.
To perform a melee attack, you can press the middle mouse button on PC or R3 on consoles. This will perform the heavy attack of the melee weapon you are using at that time. While all melee weapons have different heavy attacks, there are some commonalities that you should be aware of if you are to get the most out of this form of attack.
Counter combo and extra damage
When performing a heavy attack, you are essentially spending your combo meter. In return, you get a damage multiplier equal to your combo meter. So if you have a 2x combo meter, you will get 2x damage multiplier. This means you can create a combo counter using regular melee attacks against smaller enemies, and then unleash a devastating heavy attack against a more powerful enemy. You can still perform heavy attacks without a combo meter, and they'll hit hard, but they won't be as hard-hitting as they could be.
To build a combo meter, you just need to perform normal melee attacks against enemies, and each successful hit will add up to your combo meter. After a period of not hitting enemies with a melee attack, the counter will be reset. You can find your combo meter in the lower left corner of the HUD.
It is possible to reduce this consumption on your combo meter by using mods such as Focus Energy, or by taking advantage of the Zenurik Focus tree and using Inner Might to make your combo meter rank faster. Alternatively, the Naramon tree will allow you to delay losing your combo meter, making it easier to hold high values until you find a suitable target.
All heavy attacks have liquidation, which is the time it takes to perform the attack from the start of the animation until actually doing damage to an enemy. This will vary from weapon to weapon, and during this time you are susceptible to status effects, so there is a possibility that the liquidation will be interrupted if you are stunned.