Is there a formula for chance to hit in pvp? Like taking into account both player's levels, my AR and their defence? (think those would be all the factors - don't care about blocking, that's easy to take into account).
Yeah, fair enough, but I think you're bright enough to realise it is the first and we don't make formulae more complicated around here just for the heck of it
But don't go moving that *2 up to the front. All divisions in D2 are integer divisions, ie rounded down. Being completely precise it is
%chance = 100 * AR / (AR + DR) * 2 * alvl / (alvl + dlvl)
in that order, ignoring remainders after each division.
Example, clvl 60 attacker, 5432 AR, clvl 57 defender, DR 2345: