Hero bug deals millions of damage to bosses when sold (explanation in description)

You may get removed from leaderboards if you use this, be warned. Only level 14+ heroes work on solo, level 20 will damage less than lvl 14.
explanation:
In Bloons TD 6 (BTD 6), the boss "Lych" has a mechanic where it heals based on the tiers of towers sold. The healing calculation is as follows:
1. **Healing Calculation**:
Heal = tiers * boss_hp
Here, `tiers` is the number of tiers of the tower being sold, and `boss_hp` is the current health of the boss.
2. **Overflow Issue**:
The game uses a 32-bit signed integer to store the heal value.
The maximum value a 32-bit signed integer can hold is 2,147,483,647.
If the heal value exceeds this maximum, it will overflow. In programming, when a signed integer overflows, it wraps around to a negative value due to the way integer overflow is handled in two's complement representation.
3. **Scenario Analysis**:
*Scenario 1: Selling a Tower with 15 Tiers*
Let's say the boss has 144 million health (144,000,000).
You sell a tower with 15 tiers (level 14 hero).
Calculation: heal = 15 * 144,000,000 = 2,160,000,000
Since 2,160,000,000 exceeds 2,147,483,647 (the maximum for a 32-bit signed integer), an overflow occurs.
After overflow, heal wraps around to a negative value, specifically -2,136,313,344.
Final heal = -2,136,313,344 / 100 = -21,363,133.44 (approximated)
Therefore, the boss would effectively receive damage of approximately 21.36 million hp due to the negative heal.
*Scenario 2: Selling a Tower with 13 Tiers*
Calculation: heal = 13 * 144,000,000 = 1,872,000,000
1,872,000,000 is less than 2,147,483,647, so no overflow occurs.
Final heal = 1,872,000,000 / 100 = 18,720,000
In this case, the boss would heal for approximately 18.72 million hp.
4. **Conclusion**:
Selling a tower with 15 tiers causes the heal calculation to overflow a 32-bit signed integer when multiplied with the boss's health.
The overflow results in a negative heal value, which translates to damage against the boss in the game mechanics.
Selling a tower with 13 tiers or any lower number of tiers will not cause an overflow, and the heal value will be positive, resulting in actual healing for the boss.

[@AJThePurpleBoy]

Bro did NOT want to get Obyn down

[@ohhi687itsme8]

bro did -3M damage

[@Lawrence_Zhou]

that's crazy

[@lucifer_morningstar..]

came from ISAB

[@TechSY730]

And this is what can happen if you fail to use a big enough data type and don't use saturated math operators. 😁

[@supremechaosbeing2696]

i mean does it work without mods to place more heroes? your reasoning sounds like it should but why not just test it on a real game? if all I have to do is buy 14 levels on a hero then that sounds easy as hell

[@boartd6]

Yes, you can buy level to lvl14 and sell a hero 7 times. In this video I just had 7 heroes placed down to just have to sell them all so d20 subgon could kill the boss without 7 lych souls spawning.

[@Dartus_MonkusIII]

So this bug only works on the tier 5 elite lych that had 144 mil hp? If you sold the hero on a tier 5 normal lych the boss would heal normaly correct?

[@Floeflayfloe]

Yeah the number wouldn’t be big enough to be negative

[@sayoriigd]

i aint smart enough for this wtf

[@christophergovek3699]

so how do you get multiple heros

[@boartd6]

Mods, in a real game you would buy and sell heroes 7 times which does the same job.

[@somnathbhattacharya2819]

Dammnnnn

[@mikshake5774]

thats funny as shit wow

[@chartreusecharon]

fake boar fr

[@boartd6]

Holy Charon real?