（第 19 页）
- Pin will jump out of the ground attempting to ram the player, then burrow back in.
- Sometimes can fire four tears diagonally from the last section of its body when jumping out of the ground or/and when burrowing back into the ground.
- Occasionally sticks its head out of the ground in order to fire an explosive projectile. After doing this attack, Pin will always jump out of the same spot he was when firing, making it easy to predict.
- Each segment of Pin can be individually damaged, so a single piercing tear could possibly hit Pin multiple times.
- Pin ingame.png
- Delirium Pin.png
Pin as one of Delirium's forms.
- The Frail is the posthumous version of it, and Scolex is the alternate version.
- Pin was added in the Wrath of the Lamb DLC for the original Binding of Isaac.
- In the original Binding of Isaac, Pin had a black champion alternative which shot 6 shots instead of IPECAC shots. This version of Pin doesn't seem to exist in Rebirth.
- Pin is based off the pinworm, an internal parasite.
- Pin is likely a reference to Lanmola, a boss from The Legend of Zelda: A Link to the Past; as nearly all attacks are the same.
漏洞：If you fire immediately upon entering the Boss Room, rarely, you can damage Pin before it emerges.
漏洞： If Pin is under the effects of Broken Modem in mid-air, its jump will be stopped and it will fall.
（第 19 页）
- 头节从地里跳出，冲向角色，然后钻进地面，能对角色造成接触伤害。如果头节被爆炸伤害了的话, he will be deflected back from the explosion when in midair.
- 头节偶尔将尾巴伸出地面，向角色的位置抛射3颗爆炸眼泪（类似 吐根吐根）。
漏洞： In Hard and Greedier Mode, black champion Scolex's sprite will be replaced with that of a second form Frail, who has an upside-down tail. This is primarily a visual bug and the Frail will have all of Scolex's attacks and AI, though the tail's hitbox will be slightly misplaced. However, when it sticks its tail out of the ground to attack, the tail will be invincible, and when it sticks its head out of the ground, it is able to be harmed.
漏洞：When Scolex is slowed, some of his body parts may detach or won't even show up - they will only be visible while entering the ground (especially the tail).
漏洞：If the final vulnerable segment of Scolex's tail is destroyed using the Chaos Card, the boss will glitch and become harder to kill. The tail will appear again if his head gets bombed or he hits Isaac.
漏洞：If you petrify Scolex (with Mom's Contacts or other similar items) when it is in mid-air, you can damage any segment of its body.
漏洞：If you fire immediately upon entering the Boss Room, rarely, you can damage Scolex before it emerges.
漏洞： If Scolex is under the effects of Broken Modem in mid-air, his jump will be stopped and he will fall.
- Scolex ingame butt.png
- 20170218184911 1.jpg
Scolex bugged with its sprite replaced by The Frail.
- Scolex can be considered an older or younger version of Pin, but not a posthumous one (that title goes to The Frail).
- A scolex is the name given to the head of a tapeworm.
- Scolex was present in the original Binding of Isaac.
- Compared to the original Binding of Isaac, Scolex's head and tail attacks are swapped.
（第 20 页）
- In the first phase, The Frail's attacks are identical to Pin's. Upon running out of health, The Frail becomes skeletal, beginning the second phase.
- In the second phase, The Frail has three attacks:
- Jumps out of the ground at Isaac, firing four tears from the last section of its body that each split into four more tears that either travel diagonally or straight.
- Sticks its head out of the ground, then fires a rotating Brimstone laser at Isaac.
- Alternatively he will turn to Isaac to fire a quick, non-moving Brimstone laser 3 times before stopping.
- Sticks its tail out of the ground, then fires a burst of spectral tears in all directions which leave small puddles of slowing white Creep where they land.
- Black:Starts in its second phase.
漏洞： If The Frail is under the effects of Broken Modem in mid-air, its jump will be stopped and it will fall.
- Thefrail ingame.png
The Frail ingame.
- Thefrail ingame secondphase.png
The Frail in its second phase.
- Delirium The Frail.png
The Frail as one of Delirium's forms.