How does off duty work bc I can’t use some characters when off duty and Idk why
That’s pretty much all there is to it, really. In war, there can be up to 5 heroes off-duty for any particular war, meaning neither guild can use those heroes when making attacks. In heist, the number is somewhere over 80 (!), and no one can use any of those heroes in a heist for that day. Off-duty heroes in war seem mostly, if not entirely, random; off-duty heroes in heist tend to be heroes that are most often used by players, so it’s pretty common for really popular heroes to be available for heist only a few days per month.
In theory, having (semi-)random off-duty heroes is supposed to encourage players to use a wider variety of heroes; in practice, because most players can only afford to level up a small number of heroes anyway, if one or two of a player’s strongest heroes wind up off-duty in war, they just attack a weaker opponent than usual, while I suspect the ridiculous number of off-duty heroes in heist is one reason that mode is so unpopular.