View source for Charge Beam additional effect chance glitch

The '''Charge Beam additional effect chance glitch''' is a glitch in the [[Generation]] {{gen|V}}, {{gen|VI}}, {{gen|VII}}, and {{gen|VIII}} [[core series]] games.

It first appeared in {{game|Black and White|s}} and appeared in all subsequent core series games until {{g|Scarlet and Violet}}, except {{LGPE}} (due to Charge Beam not being present in that pair of games). It was fixed in Pokémon Scarlet and Violet.

==Effect==
If the user has {{a|Serene Grace}} and uses {{m|Charge Beam}} while its side is under the effect of the rainbow from the combination of {{m|Fire Pledge}} and {{m|Water Pledge}}, the additional effect chance for Charge Beam will overflow and become 24%.<ref>[https://www.smogon.com/forums/threads/sword-shield-battle-mechanics-research.3655528/post-9076566 Post by Sasa to Sword & Shield Battle Mechanics Research on Smogon Forums]</ref>

==Explanation==
To multiply the additional effect chance due to the effects of both Serene Grace and the rainbow, a 16-bit signed integer is used. However, for moves that do not inflict [[status condition]]s, the additional effect chance is then stored in an 8-bit unsigned integer. <math inline="yes">70 \times 4 = 280</math> is greater than 255 (the maximum value for 8-bit integers); it subsequently becomes 24% when assigned to an 8-bit integer (when the most significant bits are truncated): <math inline="yes">70 \times 4 \bmod {256} = 24</math>.

This glitch would affect all moves with a base additional effect chance between 64% and 88%. However, Charge Beam is the only move with an additional effect chance within that range.

Improper truncation still occurs for moves with an additional effect chance greater than 88%, but has no noticeable effect. {{m|Icy Wind}}, for example, has an additional effect chance of 100%, which will become <math inline="yes">100 \times 4 \bmod {256} = 144</math>, which is set to 100 (just like the correct value of 400 would have).

This glitch is not present for moves that can inflict status conditions, as that percentage is consistently stored in 16-bit integers. [[Flinch]]ing is not affected either, as the Serene Grace and rainbow multipliers do not stack for flinching.

==Video==
{{YouTubeEmbed|LG0aFuU_ilc|channel/UC4G6pPuFGGK0qf6c6RrSBTA|name=パデック|normal|electric}}

==References==
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==Related articles==
{{Glitches}}

[[it:Glitch di Raggioscossa]]