Cobs potion didn't kill just some of the Inanimate Heroes. He killed some other ones from other object shows. This cause a massive affect on them. Let's take a look at the BFB, EEE, Object Overload, Brawl Of The Objects, PPT2, The Daily Object Show...
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Half of the BFB cast had died. They try to ask 4 and X to bring them back. But no luck. This was the first time they couldn't bring them back. This led to the others burying them. Some were upset. And some were angered. But one thing was in their mind, what exactly killed them?
Leafy: (sigh) I miss Firey.
Naily: How about we try recovering them?
Pencil: We tried to remember. 4, X, or 2 couldn't do it.
Naily: Oh yeah.
Cloudy: Wait! Doesn't the talking box have a recovery center?
Lightning: We tried that too. That just made the recovery centers explode.
Cloudy: Oh yeah.
Barf Bag: This Is Outrageous!! How Could Someone Do This To Us!!
Lollipop: If only we can figure out who could've done this.
Liy: Like we do an investigation.
Lollipop: Exactly!
Coiny: Now wait a minute! Nobody did this, it just randomly happened!!
Golfball: That is incorrect. According to my calculations. There is a 95.784% chance that someone might have done this!
Coiny: They Died Randomly!! We Don't Even Know What Actually Killed Them!!
Clock: Hey maybe someone sabotaged 4, X, and 2's powers so that they couldn't revive them.
Coiny: I don't think-
Golfball: Sounds like that could be the solution! Everyone Follow Me!!
*Everyone followed Golfball. Except Coiny.*
Coiny: Oh boy.
*All of them go to see 4, X, and 2.*
Tennisball: 4! X! 2!
4: Wha- What do you guys want!?
Donut: We Think Someone Might Have Sabotaged Your Powers!
2: What? That's nonsense!
X: Yeah. We're fine. Are we?
Gaty: You guys probably ate something bad that might have messed it up.
Black Hole: Maybe you injured yourself badly?
Eraser: I usually get beat down if I don't have enough sleep.
4: Guys guys. Look, I know we couldn't revive anyone earlier.
2: But that doesn't mean our power is messed up!
X: Just watch.
*4 uses their powers and kills Teardrop.*
Taco: Wha- What Did You Do That For!!?
4: Wait for it!
*Then they used their powers to recover Teardrop.*
