Well i use one mythical and i got 13 : 3 win loss ratio

Well, the opponents you get whenever you play significantly affects the ratio. As you got a pretty nice start, most probably getting the average players.

Myself, using 2 mythical items, not doing good not doing bad; average. I usually get top clan members, kitters (I stopped using them).

But +5 to all about tactics.

And also creating mechs smartly. Not putting random irrelevant stuff in your mech!