[X] My Assistant

Spark + at least exquisite pieces is what I am going for.

and after clearing them at least once, so you won't get locked out of the next one when failing an arena.

what's the best moment to start doing arenas at pfudor?
after getting spark of life?

I think PFUDOR is only possible after lv200 with spirit shield avaible or if you have great lucky and get many pieces of magnificent gear or above.

Last season i started to do PFUDOR at lv235.

with DW, it's pretty playable as soon as SoL unlocked, or even early as soon as you have 100 DW proficiency, even with all superior junks from bazzar. I rush all arenas with PFUDOR since first day for few seasons, but yes it's risky, you may locked out by next arena if you make mistake

Are there any other sources of Soul Shards in Isekai besides the tower and equip shop?

I think PFUDOR is only possible after lv200 with spirit shield avaible or if you have great lucky and get many pieces of magnificent gear or above.

Last season i started to do PFUDOR at lv235.

yes, i'm definitely not strong enough yet.
after the reset i did the tower and then tried the lvl20 arena (6 rounds) at pfudor.
i managed to clear it but i sparked 3 times and had several other near oneshot experiences.