Mega Man Zero 2/Power Room: Phoenix Magnion

For this particular mission, Elpizo is acting on a rumor that an arms factory is situated close to the Resistance Base. His scouts found reactors that give it a steady supply of electricity, and if Zero were to destroy them, it would reduce the amount of troops Neo Arcadia would have at the ready.

If you succeed with this mission, you'll discover that every single type of Pantheon in all of the first four mission areas will be eliminated, permanently. This will make a lot of the missions far easier, but hinder your chances of higher kill rates in the levels.

Unlike the other missions you can pick, this one isn't set in a linear path. In order to complete it, you need to find four reactors and destroy them. The last one you destroy will trigger the boss to appear, and also affect the difficulty of the battle. This also means you'll need use of the Escape function should you chose to come back.

There are even hidden side areas you can enter, and a higher-than-normal time limit to complete this mission and get full points, but what you need to focus on is the fastest and safest path to get there so you can come back. You'll find the Sub Tank from the Forest of Dysis is definitely your best friend here.

Entrance and Branching Paths
When you first reach the Power Room, you'll be a short distance outside. Go slightly further and you'll run into Pantheon Gunners. Blast your way through with short Charge Shots and keep dashing on.

Right after you climb a stairwell and get past a Pantheon Gunner, you'll reach a generator that sends out infinite numbers of Tellybombs, a throwback to the original Tellies from classic Mega Man. Only one comes out at a time, and one won't appear unless the last is destroyed. However, these enemies can be a severe nuisance, as they don't just fall apart when destroyed; they explode, damaging you if you get in the blast range. They home in on you, but go flying if hit by any weapon, then explode when they crash into anything.

As it so happens, a Cyber-Elf Box is right next to the first Tellybomb generator. Lure one close enough to whack it with your Z-Saber, although any weapon will do(just as long as you don't pull it to you if you use the Chain Rod). With a proper strike, it will smash into the flimsy wall blocking access to the Cyber-Elf Box and blow it apart. Then, you can obtain Cyber-Elf Stocttus from the box. Additionally, after you make four Tellybombs explode, you'll get Cyber-Elf Bomphew.

Go just a little further and climb down the ladder to find another thin wall. Knock the Tellybomb that comes out into it to open the path into the Power Room's inner chambers.

When you enter the chambers, you'll be greeted by an odd new Pantheon, the Pantheon Hopper. These Pantheons mimic prowling beast and crawl low enough to the ground to avoid Buster shots unless they're charged. If you or they get within attack range, they'll leap into the air and strike with their attack claws. Carefully slash them before they can retaliate, and keep moving.

As you head in deeper, you'll find the Power Room doesn't get any friendlier. Several pits of molten slag are located throughout the area. One wrong step into them means immediate death without Putick's help. Be very cautious as you jump over them, and even more wary of the Tellybombs coming out to attack between the pits.

Signaloid Terrors
When you get across the slag smelter pits, you'll reach an area filled with Tellybombs above, but an even worse set of enemies below. Signaloids, stationary attack cannons reside here, but have a special gimmick to their attacks. They can interchange their attacks between all three elements, Fire, Thunder, and Ice, depending on the light shown. Its color and attack pattern correspond with the element you are currently wielding, it changes colors if you switch to a different element. Red means Fire, yellow, Thunder, and blue, Ice. When it's red, it shoots flames from its right or left side (depending on which side of it you stand in front of) like a flamethrower and then shoots a small fireball. When it's blue, it shoots two snowflakes that rebound off surfaces in a very hectic manner. When it's yellow, it shoots an electric blast, which has a short range but splits into two blasts when it is in the same vertical axis you're on. All three attacks do evil amounts of damage, and Signaloids can even switch elements at will. Not only that, but they don't even constitute a Cyber-Elf here, and they only guard a Life Energy Capsule down at the end of the lower path, so it's best to avoid the Signaloids altogether. Even without an element equipped, they remain on the color they're currently set at, so memorize what they do, because they will appear lot more in the game.