A staple of the classic series, E Tanks were introduced in Mega Man 2 and quickly became the Blue Bomber’s go-to method of healing. With very few exceptions, every game in the mainline Mega Man series from that point on featured E Tanks in some capacity. After all, with enemies irregularly dropping health pellets, players needed some way to control their Life Bar at any given moment. Fully recovering all of Mega Man's health when used, E Tanks make getting through the classic series all the more manageable.
But like most things in classic Mega Man, E Tanks were not deemed fit to return for the franchise’s jump into 16-bit: Mega Man X. MMX was a radical departure for Rockman, one that arguably split the series into before & after. Along with featuring a progression system & a darker story, Mega Man X replaces E Tanks with Sub-Tanks– unlockable items that store health for later.
Sub-Tanks are more strategic in use than E Tanks. While they’re not a one & done deal, drinking a Sub-Tank drains it full. Players need to be mindful of how much health X can afford to restore at any given time, lending some element of foresight to Tank system. There are four scattered throughout the game and most series veterans will swear by them– especially when it comes to the final boss fights against Sigma. A Sub-Tank can be the difference between life & death for X.
4 Flame Mammoth
It should be kept in mind that while there are Sub-Tanks that can be found at the very start of the game without the need for any upgrades, suffering through stages without the dash isn’t worth it. Instead, players should immediately head to Chill Penguin’s stage, find the Leg Parts, and beat the boss for good measure.
Now that Chill Penguin has been defeated, Flame Mammoth’s stage will be frozen over. Along with having access to a Heart Tank, a sub-tank will be tucked towards the leftmost wall inside the former lava room. Dash jump towards the wall and X’s leg parts will kick through the blocks guarding the Sub-Tank. Grab the tank and start stashing away health reserves for later.
3 Storm Eagle
Storm Eagle’s Sub-Tank is really no hassle to get your hands on, but it’s at least tied to a fairly memorable set-piece and constitutes as one of Mega Man X’s more clever secrets. Following the rotating levators at the start of the stage, X will be able to walk on top of the airport. As soon as players run into a turret, kill it and stand on top of it.
The turret’s platform will rise and X will be face to face with another room. Shoot through the glass blocking the room and X will be able to find a Sub-Tank inside. All things considered, it’s a charming little Easter egg and a fun way of hiding a Sub-Tank. Shooting your way through the glass as it breaks around X makes for some excellent visual flair and a very memorable Sub-Tank encounter. Worth noting, Storm Eagle’s stage also featured a Heart Tank and an armor upgrade, so be on the lookout.
2 Armored Armadillo
Roughly halfway through Armored Armadillo’s stage, X will be chased by the Mole Bearer. With spikes attached to its front, the Mole Bearer can very easily tear X apart. Players need to be quick to survive its onslaught, but if X holds back as he’s sliding down the pit into the encounter with the Mole Bearer, he can actually get behind him.
Hidden behind the Mole Bearer is none other than a Sub-Tank. Unfortunately, letting the Mole-Bearer plow ahead means risking a lost Heart Tank. It’s smarter to take out the Mole Bearer, double back for the Sub-Tank, and then head to the Heart Tank. Otherwise, you’re looking at more than one playthrough of Armored Armadillo’s stage (and even more than that for anyone aiming for the Hadoken.)
1 Spark Mandrill
Getting the Sub-Tank in Spark Mandrill’s stage means beating Boomer Kuwanger beforehand in order to get his boss weapon, but it’s arguably the easiest Sub-Tank to grab in the game. All players need to do is properly line up their Boomerang Cutter and the blade will hook the Sub-Tank, carrying it back to X. With no enemies around to hurt X & the tank located at the start of the stage, players can take as much time as they need to grab their Sub-Tank.
With all four Sub-Tanks in hand, the Sigma stages shouldn’t pose too much of a problem. Mega Man X also features a fairly forgiving boss rush compared to other games. That said, the three part finale against Sigma is quite daunting and those four Sub-Tanks will certainly come in handy. Don’t be surprised if X needs to guzzle down each tank before credits roll. Thankfully, the final stage features a very convenient grinding spot for health & energy drops.