In order to play the stage, the player needs to have completed the Silver Episode in regular gameplay. Once cleared, the Shadow Boss Attack can be selected in the Episode Select. Any Level Up Items obtained in the Silver Episode can be used for this level.
The objective in this level is for the player to defeat the boss or all waves of enemies in each section to progress through the stage. In sections where the player has to defeat the boss, the enemies that spawn are optional for the player to defeat for bonus points. Any Rings obtained are carried over to the next section.
The first section of the level is the battle against Iblis in his first phase at the future timeline. The fight here is identical to the regular fight, although three Iblis Biters will spawn in the arena that will likely interfere with the player's progress in defeating Iblis. If an Iblis Biter is defeated, another one will spawn to take its place. It should be noted that the player cannot use Psychokinesis on the Iblis Biters and throw them to damage Iblis. The player moves on to the next section once Iblis is defeated.
The second section of the level is an enemy wave attack, taking place in the same area where Shadow would normally fight Mephiles Phase 2. The arena has been modified with the addition of more platforms, some which enemies may spawn on and some which hold Containers and other objects the player can use Psychokinesis on to attack the enemies. When all objects on a platform have been thrown with Psychokinesis, another set of objects will respawn on that platform to take their place eventually. After a wave of enemies is destroyed, the next group of enemies will spawn. Enemies that spawn here include Iblis Biters, Iblis Takers, Gazers, Golems, Iblis Worms, Stalkers, and Titans. Once all enemies are defeated, the player is able to proceed to the next section.
The next section takes place in Castle Town where the player fights against Sonic the Hedgehog. Like the original boss fight, there are no additional enemies. Once Sonic is defeated, the player can move on to the next section.
The next battle is against the Egg-Genesis at White Acropolis. Aside from the enemies that spawn from the Egg-Genesis, there are no new enemies. The Egg-Genesis behaves differently in this level than in the regular boss fight, being able to fire charged laser shots right from the beginning of the battle. Defeating the Egg-Genesis here will allow Silver to progress to the next section.
The next section is an enemy wave attack and it takes place in the same area where Sonic would normally fight his version of the Egg-Cerberus. Much like the previous enemy attack wave section, the arena has been modified to include more platforms, some containing enemy spawn points and some containing objects (such as Containers) that can be used against the enemies with Psychokinesis. The enemies that spawn here are all Dr. Eggman robots, including the Egg Bomber, Egg Buster, Egg Cannon, Egg Chaser, Egg Gunner, Egg Stinger and Egg Sweeper.
In the next section, the player simply battles against Shadow the Hedgehog without any additional enemies and his attack pattern remains unchanged from the regular boss fight. Once Shadow is defeated, the player can move on to the next section.
The next section is an enemy wave attack that takes place in the future timeline again, in the same area where Shadow would normally fight Mephiles Phase 1. Like before, the arena has been modified with additional platforms with Containers. Again, only Eggman's robots appear as enemies in this section (although with the addition of Egg Walkers and an Egg Keeper). Defeating all enemies here will allow the player to progress to the next section.
In the last section of the level, the player battles against the third phase of Iblis. Unlike the original boss fight, there are two platforms, each with a Titan and a Golem enemy that constantly attacks the player, and Iblis behaves slightly differently, being able to fire more often. Defeating Iblis here will end the level.