a) alrdy done in maintenance
b) learn to play pvp tbh^^ its no way impossible to kill stage10 in trial arena, learn the starting atk pattern, counter it, cc lock, repeat, done. The stage 10 can be easily killed with idk 1,7k AP or so
c) i returned when last arena was resetted (archer patch), got to 1,9k ap till now, so it is nowhere to impossible to clear trial arena till it resets next AND in addition to that... it is meant to be a challenge, not to be cleared by a 1,4k newbie on the first day...
€: just cleared first five stage 10 with 2 stars each (not rly tryharded) before the maintenance hit, it took me +- 40min