The player's first encounter with Zeena is at the end of Frozen Factory Zone 2 on a snow-covered planetoid. Sonic will remain inside of the snowball for the duration of this battle, so the player must rely on the limited movement options available to them in this state to fight Zeena.
During the battle, Zeena will bury herself into the snow and summon large snowmen out of the ground. These snowmen will not actually attack Sonic, but they need to be destroyed before the player can attack Zeena. The player does this by ramming into them with the snowball, but if the player takes too long to do this, the snowmen will sink back down and the player has to start over with detroying the snowmen. After destroying all the snowmen, Zeena will pop out of the last one and begin running away. This leaves her vulnerable to attack, so the player will simply need to spin dash into her to cause damage.
The battle will then go through two more phases identical to the one mentioned above, except that with each round there will be more snowmen for the player to destroy. There will also be bomb-headed snowmen thrown into the mix to trip the player up, and while they won't exactly damage the player when they're hit, they will cause the round to reset if struck by accident; wasting precious time.
The bomb-headed snowman is easily identified by it's darker-colored, metallic head & lit fuse, but it is advised that the player still pay close attention while spin-dashing around as the bomb-headed snowmen like to pop up near the ones they have to destroy.
After completing three rounds with these processes, Zeena will be defeated.
Similar to the previous boss, this boss takes place at the end of Frozen Factory Zone 4 on a planetoid, except that this time, the planetoid is covered in ice, making it harder for the player to get a foothold during the battle.
In this boss battle, Zeena will fight the player directly. During the battle, Zeena will use a Snowman Mech head like a mace and swing it around in an attempt to smash the player. It will start out slow, but will eventually pick up speed; making it hard to dodge. Zeena will also slowly move towards Sonic while spinning, so it is advised that the player keeps his/hers distance which possible.
Zeena can be targeted essentially at any time during this fight, but it is recommended that the player try to get in to attack her before she gets spinning too fast, as it is easier to land a hit then. After hitting her three times, Zeena will enter her second phase, where she will bring down two Snowman Mech heads that she will swing around via energy chains around the whole planetoid. If Sonic makes contact with these energy chains it will damage the player, but they can be jumped over. After hitting Zeena three more times, she will be defeated again.
Zeena is fought in the NiGHTMARE Zone in a battle similar to her fight in Zone 2, but with a few differences. Sonic will not be inside of a snowball, and Zeena will be riding on the second-level Nightmaren Clawz. To defeat her, first the player must get rid of all of the mouse bombs in the area, then they must attack Clawz.
Frozen Factory Zone Boss
Zeena's boss in the Nintendo 3DS version of the game takes place in a blizzard-bombarded arena. During the battle, Zeena will be sitting atop of a large Snowman Mech at the corner of the arena. Over the course of the battle, wind will be blowing against Sonic, pushing the player back, although it can be bypassed by running against it to get up close to Zeena. When Sonic gets as close as he can to the Snowman Mech, he has to use the Homing Attack on the blue circle on the belly of the Snowman Mech to deal damage to Zeena. However, while the player is making his/her way up to the Snowman Mech, the Snowman Mech will be firing out smaller Snowman bots that will move around on the field. These smaller enemies can draw the Homing Attack target lock-on away from the Snowman Mech, and will damage the player if they run into Sonic.
After hitting the Snowman Mech three times, it will release an Ivory Wisp that the player can use to transform ito the Ivory Lightning and deal some damage to Zeena. Any Snowman bot that the player hits with the Ivory Lightning's lightning grapple will turn into floating snowman heads that will fly up. The player can then use these Snowman bots to grapple up to a couple of coils, which the player can then use to attack Zeena directly and deal massive damage. When the Color Power runs out, the player can go back to hitting on the Snowman Mech's belly. Repeat the mentioned strategy and Zeena will be defeated.