The Spike gear is one of only two hats in the game that is animated. It technically consists of two sprites, one being the round base with two eyes on it, the other being the actual spike part. The spike part is always turning, while the base always remains attached to the player and faces the same way the player does.
The Spike Gear reflects 45% of damage done to the player wearing it back to the player who dealt the damage.
Below is a Damage table. On the left damage done. On the right, damage reflected by the Spike Gear.
The Corrupt X Wings reflect 25% of damage done to the player wearing it, so combining the Corrupt X Wings with the Spike Gear will allow you to reflect 70% damage back to the player hitting you. Assuming you have lots of food, this can make outlasting the opponent very easy because there is no way he can hurt you without greatly hurting himself.
Keep in mind that you cannot rely on the Spike+Corrupt X build without actually fighting the other player, because in any event he will still be able to kill you before the gear kills him.
Theoretically combining the Spike Gear, Sawblade and Shield can be extroardinarilly effective because if a player hits you he may actually recieve more damage than he inflicts as the Sawblade always inflicts a solid 5 damage points on players who hit you.