The damage dealt by this tear is ten times Isaac's damage, plus a flat 10 damage.
The shot has an additional 1.5x size multiplier on top of damage-increased size.
Sets Isaac's health to half a heart with each use (half a Soul Heart if these are present but there are no Red Heart containers). This also removes any other Soul or Black Hearts, but not Eternal Hearts.
If Isaac has no Red Hearts and at least one Bone Heart, only an empty Bone Heart remains.
Upon taking damage, this item turns into Broken Glass Cannon, and Isaac will lose an additional 2 hearts of health on top of the damage he already took. Isaac gains 1.5 range and leaves a trail of red creep behind him, identical to the effects of Anemic.
If the damage from breaking Glass Cannon would result in death, Isaac will remain at half a heart, gaining half a soul heart if necessary. This does not apply if the damage Isaac took would be lethal before the extra damage is taken.
The item recharges actively after use, similar to items like The Boomerang, allowing repeated usage within the same room.
Shooting the Glass Cannon gives a slight knockback effect to Isaac, which can be dangerous in rooms with obstacles like spikes or Fire Places.
Chocolate Milk: The current charge of Chocolate Milk affects Glass Cannon.
Godhead: Creates a giant aura around Glass Cannon tears that almost fills up normal sized rooms.
Lachryphagy: Glass Cannon will fire giant Lachryphagy tears. Tears are harder to feed as they will burst very quickly but they can be fed if you fire tears beforehand and then fire Glass Cannon into those tears.
Holy Mantle: Doesn't prevent damage done by Glass Cannon, but will protect against other types of damage.
Ipecac: As the Glass Cannon tears are so large, even a modest damage increase or a single tear size increasing item is likely to render the tear unable to damage enemies, their explosions too far from them.
Soy Milk: Reduces damage of shots, no effect on charge time.
Trisagion: Fires normal Trisagion beams that do not have increased damage.
The Wafer: Doesn't reduce the damage taken while Glass Cannon is held.
Glass Cannon is a term used in video games for a character or entity that deals high amounts of damage but has very low defense.
Originally, Glass Cannon would only reduce Red Hearts, so if Isaac had a large number of Soul/Black Hearts, the item would essentially be free damage. The item would later be patched to also remove other types of health as well, making it a lot more situational.
PC 9BJ3 WWHL (First floor Treasure Room, north of spawn)
Switch JAWB DBJ6 (First Golden Treasure Room)
PS4 MAYW FFY4 (First Treasure Room, west of spawn)
Glass Cannon can be used to steal Devil Room items by using it to set your health to half of a Soul Heart or no health at all before you die. In the latter case, picking up any item that isn't a health upgrade will kill Isaac.
If Tainted Forgotten takes damage with the cannon held above his head, he will be unable to fire and unable to attack. Exiting and continuing will fix this.