[Overview]:

VAAAAMPIIIRE RAAAMPAAAAAGE!

This build is designed to make easy, repeated use of [Life Strike] while keeping attack speed and damage as high as possible.

Activate "Apply Conditionals" above to view numbers for full rampage.

How To Use:

• build your combo counter to level 4 or 5
• trigger Pennant's awesome attack speed by landing a heavy attack
• build your combo counter to level 12
• rampage through endless mobs while stealing life at will

Connecting with a heavy attack will expend ~1 level of combo multiplier, fill your warframe's health bar, and re-up [Pennant]'s attack speed boost. With 90% heavy attack efficiency, this build will keep the melee combo multiplier high even as you perform many heavy attacks. [Pennant]'s speed bonus on heavy attack is ridiculous, and it lasts a whopping 46 seconds with a combo multiplier of 12. Soon after using a heavy attack, it is important to remember to use regular attacks to build the combo counter back to max, which should be easy with [Pennant]'s speed boost active. Heavy attack can be used several times in a row without any danger of breaking the rampage, as each heavy attack will cost only ~1 level of combo multiplier.

Naramon school of focus with Power Spike active is recommended to keep the rampage alive without worry. Losing a few kills from the combo multiplier is no big deal, but having it reset to 0 can be an annoying setback due to [Pennant]'s extremely slow unmodified attack speed.

Mod Choices:

[Primed Pressure Point]
[Blood Rush]
High damage multiplier + high combo multiplier == high damage. These mods are better than the Sacrificial mods in this build because the build is designed to be operated at or near max combo counter. [Blood Rush] and [Primed Pressure Point] easily outshine [Sacrificial Steel] and [Sacrificial Pressure] under those circumstances. Possibly, if you were planning to fight Sentients, you would want to use the Sacrificial mods here instead, though it would require additional forma.

[Reflex Coil]
[Focus Energy]
Maximum Heavy Attack Efficiency. 'Nuff said.
Oh, and a bit of electric damage too.
You could swap one of these out in favor of additional damage, but keeping the rampage active would then become more difficult and additional forma would be required. Doing so would also limit the frequency with which [Life Strike] could be used while maintaining the rampage. I keep both equipped because I use this build for all the carefree health vamp it can provide.

[Primed Fever Strike]
This mod generates significantly more damage than [Gladiator Might], which is the other mod I tried here. Additionally, in combination with [Focus Energy], it provides the Corrosive damage type, which is a desirable damage type on this weapon.

[Life Strike]
This mod was the whole point of the build: get the best best lifestealing possible.

[Amalgam Organ Shatter]
The critical damage provided by this mod is a beast in combination with [Blood Rush]. The boost to heavy attack wind up speed is very nice for whipping out a [Life Strike] as quickly as possible.

[Killing Blow]
This mod is where you might switch things up? I keep this on mainly for the heavy attack wind up speed. Other mods, like [Gladiator Might], [Primed Smite Grineer], or an elemental damage mod would provide similar damage capabilities but without providing the wind up speed. The damage bonuses on those other mods do apply to regular attacks in addition to heavy attacks, so there could be some benefit in using them instead. My goal with this build was to make [Life Strike] as profitable as possible, and [Killing Blow] contributes both the best damage and the best heavy attack speed to that purpose.