I couldn't miss the chance to practice my drawing!
The second form glitch is a glitch in 2D versions of Final Fantasy IV where a player can prevent certain bosses from entering their second forms during a fight. The glitch works because the transformation is a counter, but will never trigger if a spell is reflected off a character onto the boss. The first boss susceptible to this tactic is the Mom Bomb fought at Mt. Hobs. The Elements fought in the Giant of Babil are vulnerable; in essence, one only has to kill Milon, who has about 20,000 HP. The Dark Elf, fought in Cave Magnes, and Zeromus, who only has 61,000 HP, can also be prevented from entering their second forms.
The glitch has been fixed in the remakes since the US GBA version. However, a second way to skip some second forms is possible for bosses such as Zeromus. Due to how bugged the ATB system is in the GBA version, it is possible for a party of very fast physical attackers, ideally Edge, Yang, Cecil, Kain and a higher speed Cid, to kill Zeromus with physical attacks by inflicting only 61,000 points of damage. To do this, the player must kill him before he gets another turn after Big Bang, as that is when his AI script sets up the counter. Since continuous physical attacks delay other turns in the GBA version, this isn't difficult at high levels with Lunar Ruins equipment. This has been fixed in the PSP version.