2019-11-23T04:00:00Z
incrInvisibility(20); //percent
if isWinterGhillieSuit() && ! isSnowyGround() { decrInvisibility(15); }
if isForestGhillieSuit() && isSnowyGround() { decrInvisibility(15); }
// etc
Edit. I updated the title of this feature request after reading the comments. I’m sorry if this was misleading.