Suicide content and Arena grind.
So i comeback to the game after a very long time, so now my 2 stars are useless in arena (of course this event was helpful but i dont think it will happen soon again) so my first question is, What rarity star champions should i upgrade to start the arena grind? My four stars? Or i should i just upgrade my 5 stars, i still dont have any 6 stars. And my second question is in what content the suicide masteries are absolutely unusable? Because id like to get the masteries but i don't want to keep wasting my runes with this weird system that kabam implemented. So yeah help me with what champions should i focus on the arena grind and what content should i not use the suicide masteries.