Evil Chip (Battle Chip)

Evil Chips are Battle Chips in MegaMan Battle Network 4 that can only be used by MegaMan.EXE when his spirit has been significantly put under control of his Dark Soul. To open the entrance to Black Earth, the player must have the following 5 Evil Chips: Muramasa, Anubis, ElemDark, BlakWing, and BugCharg/BugCurse.

These chips do not turn a NetNavi evil, but like the DS version of Navi chips they can only be used by Dark Navis.

Battle Chips
When a DS Navi is defeated (or when achieving the specific busting level against an SP Navi), MegaMan will receive that Navi's DS Chip. DS chips, like Evil Chips, can only be used by dark NetNavis. The power of these DS Navi chips also depends on MegaMan's DarkSoul Level. In MegaMan Battle Network 5, MegaMan can't use these chips if he isn't in Dark Mode (gained by using Dark Chips before), but other Navis (only in Liberation Missions) can use them. 

Trivia

 * The Blackwing chip's attack is a direct copy of the attack which the DarkMan chips in MegaMan Battle Network 3 use.