Thunder Shield

The Lightning Shield (サンダーバリア), also known Thunder Shield, Thunder (サンダー) and Magnetic Shield (磁力バリア), is one of the shield variants in the Sonic the Hedgehog series that the player is able to pick up by breaking an Item Box with a lightning bolt or blue shield symbol on it. Like every shield, the player gets then surrounded by large bubble when obtaining it, with the Lightning Shield having electronic effects on it. The most known effect of Lightning Shield is to attract Rings that are close to the player like a magnetic force. In some games, the player is able to do double jump and even reject all electronic obstacles and energy projectiles that enemies are shooting at the player wtih. Like the traditional shield, it can also adsorb one hit without the player losing Rings or life when touching enemies or obstacles.

The Lightning Shield was first introduced in Sonic the Hedgehog 3, as well as its locked-on form, Sonic 3 & Knuckles. Since then, the Lightning Shield has become one of the most recurring shield power-ups in the series. The functionality of Lightning Shield has been varied only in few games and some of it's features from first appearance are taken out (and later bring back) or advanced to separated movement.

Sonic the Hedgehog 3 & Knuckles
In the first appearance on Sonic the Hedgehog 3 and it's add-on continuation Sonic & Knuckles, the Lighting Shield is found in white monitors with a white thunder bolt symbol on it. After breaking the monitor, a huge electrocuted shield surrounds the player with a rotating effect on it. It has multiple features and it can be found in most of the Zones in both games. It can be also obtained from Bonus Stages, where it is found in golden gumballs with a B-letter on them.

In this game, the Lightning Shield absorbs one hit against enemies and obstacles, and magnetically attract Rings nearby in the Zone until they catch the fast moving player. However, if the player hits enemy or obstacle while Rings are attracted to the player, thus causing the Lightning Shield to vanish, the Rings will stop following the player and bounce everywhere and disappear after a while. It also deflects shots from badniks that use energy weapons (such as Blastoids) but not lasers. However, the player can easily touch and run past Electric Generators in Flying Battery Zone and Death Egg Zone without harm with the Lighting Shield on. Exclusively, if the player is playing as Sonic the Hedgehog, by pressing A-, B- or C-button during a Spin Jump, the Lightning Shield allows the player to perform double jump.

Like every other elemental shield in the game, the player will lose the Lightning Shield after touching water. When this happens, the water will flash for a split second, representing the electricity from the shield being dispersed in the water. Strangely, the shield is not lost when the player's character skims across the surface of the water in the Hydrocity Zone.

Sonic R
The Lightning Shield's (called Thunder in the Japanese version of the game) next appearance was in Sonic R, where it was yellow in color. It can be found on Item Panels on the tracks with yellow orbs on them. After obtaining a Lightning Shield, it will accumulate all Rings nearby the player. However, if the player falls into the water while having the Lightning Shield equipped, he/she will lose it.

Sonic R is the first game, where the Lightning Shield does not allow the player to double jump as Sonic, as only Sonic can perform the double jump in the game without the Lightning Shield.

Sonic Adventure Series
The Lightning Shield (renamed Magnetic Shield in the games) later appeared in both Sonic Adventure and Sonic Adventure 2, and their remakes, Sonic Adventure DX: Director's Cut and Sonic Adventure 2: Battle, as one of Item Box power-ups. In this game, the Magnetic Shield can be found in item boxes that has a blue electrical orb symbol on them. When obtaining a Magnetic Shield, it creates a plasma ball effect around the player.

In this game, the Magnetic Shield does not grant a double jump to any playable character while having it. However, like in previous games, it can attract nearby Rings by default and, like a normal shield, it absorbs one hit after the player touches any harmful obstacles or enemies. In Sonic Adventure 2, if the player runs through the Point Marker with over 90 Rings in hand, it automatically gives either a normal Shield or Magnetic Shield randomly to the player.

Sonic Advance series
The Magnetic Shield (again renamed as Magnetic Barrier) is featured in all three Sonic Advance games, where it can be found at item boxes with dark blue orb symbol on them. The appearance and effects are the same as the ones in Sonic Adventure games, as it can attracts Rings near by to the player and absorbs one hit, but once again doesn't feature double jump for any playable characters.

Shadow the Hedgehog
Magnetic Barrier later appears, along with Heat Barrier and a normal dark green Barrier in Shadow the Hedgehog, where it can be acquired as a power-up from containers or once again activated by breaking an Item Box with dark blue orb as symbol. It functions similarly like in Sonic Adventure games as attracting Rings into Shadow and disappears, when the player gets hit once or falling to the bottomless pit.

Sonic Rush games
The Magnetic Barrier has also made appearances in both Sonic Rush and Sonic Rush Adventure, where it's effects, functionality, and appearance are almost identical from Sonic Advance games, as it can be found at Item Boxes, attracts Rings near by and absorbs one hit by enemies or obstacles.

Sonic Riders series
The Magnetic Barrier has made appearances in both Sonic Riders, Sonic Riders: Zero Gravity and Sonic Free Riders as one of power-ups inside item boxes, that is able to attract nearby Rings once activating it. Some Gears may have Gear Parts with this ability. The Magnetic Barrier in Sonic Free Riders however, is not a power-up, but rather a Gear Part named Ring Eater which has identical abilities of the Magnetic Barrier.

Sonic the Hedgehog (2006)
Magnetic Shield in Sonic the Hedgehog (2006) functions more differently and is more of an ability called Thunder Guard. This ability can be activated using the Yellow Gem, that creates yellow electronic shield around Sonic. It can normally attracts nearby Rings and is protects from enemies' attacks. While it disappears after getting hit once, the Thunder Guard can be created again constantly with use of Yellow Gem.

Sonic Colors
While in Wii version of Sonic Colors item boxes along with Magnetic Shields are unexcited, they have made normal appearance along with normal dark green shields in Nintendo DS version of Sonic Colors, where they are only found at item boxes. Magnetic Shield functions similarly like it did in Sonic Advance and Sonic Rush games.

Sonic Generations
Magnetic Shield appears in Sonic Generations as Thunder Shield. In Console/PC versions of the game, after completing a certain mission for City Escape, Classic Sonic is able to buy the Thunder Shield as a Skill at the Skill Shop. It costs 4000 skill points to buy and 70 points to equip. The shield retains all of its abilities from Sonic 3 & Knuckles,  but the shield does not disappear when the player goes underwater. There are also glitches where if a player activates the double jump ability while jumping on certain springs, it would either bounce the player into an explorable part of the map with nothing in it or it will send them falling to their death in a bottomless pit.

In the Nintendo 3DS version of the aforementioned game, the Lightning Shield functions the same as it does in Sonic Adventure and Sonic Rush. It can only be found in Act 1 of Emerald Coast. However, it can also be obtained as an extra skill by playing Versus Mode online.

Sonic Lost World
The Lighting Shield is set to make appearance along with other elemental shields in the Nintendo 3DS version of upcoming Sonic Lost World, where it can be found in item boxes with dark blue orb symbols on them.

Trivia

 * Through the whole series, Sonic is the only playable character, who has been able to perform the double jump with Lighting Shield and even he could only do it with shield in two games. It then again, make progress to it's own ability, which again Sonic has been able to do in Sonic R and Wii version of Sonic Colors.
 * When the player uses Sonic Boost in Sonic Unleashed, Sonic Colors and Sonic Generations, the move attracts Rings on near close of the player similarly like Lighting Shield, which makes easier to collect them from group and string formats at high speed.