He mentioned that the fastest champ he has is 255

Is anyone else's gem mine empty with every log in?

It's not worth doing unless you can do 800 minimum. There's a few arena-viable champs that have high speed AND can do Inc Acc. One of them goes first and 400 resist might as well be 0. Heck 600 resist is nullified by 400 acc + 50% buff... 

Not to mention, in Mikage's case (who is free for everyone and not as hard as Marius to get), the fact her A3 ignores 20% resist anyway. Or god forbid a Galathir. Ignoring 20% of 600 drops their resist to below 500, and the 50% inc acc happens before the buff strip + weaken.

Feral gear and Pinpoint both have spd and acc bonuses on them. Faster with high Acc is much easier to pull off than high resist, just by the current design of the meta...

Do we even want to discuss Marius? Inc Acc on a extra turn ability, with a A2 that buff strips without triggering polymorph?

All in all, given how Inc Acc is actually seen in arena (and inc res rarely is) you gotta do 800 or more. The reason is that if you're building that much resist, you have a much lower chance to go first. You would be hard pressed to have over 300 spd, which means you're relying on Resist to stay alive till your first turn. Again, not trying to say you don't know the game but given the power creep, you should update your expectations of what is out there these days.

EDIT: Wanted to add that there's also the champs like Thor who permanently decrease resist for the whole fight and there's nothing you can do about that. Stoneskin might not even prevent it and it doesn't need acc, there's a few others with that permanent decrease resistance by x on abilities

Doesn't matter how long OP has been playing, 100pct with kram that he is early game. 

800 resist?! How is that even possible? When I hear people spout out these ridiculous high endgame numbers I can't help but wonder how it's even possible. Even if every stat on the armor pieces was somehow resist, I feel like that couldn't be done.

let's break it down.

• base resist of 90 (limited to var-gall or a few of the older dwarven legendaries, but we're aiming for theoretical maximum here)
• 6 star res chestplate w/ ascension, +125 (215 total)
• 6 star res banner w/ ascension, +125 (340)
• 6 star mythic weapon, helmet, shield, gloves, boots, amulet with 5 res rolls and maxed glyphs, 88 per piece, 528 together (868)
• 6 pieces from res or fortitude sets, 2 stoneskin, and one from either protection, supersonic, or rebirth, 180 (1048)
• 6 star infernosphere or volcardiac heart, 96 (1144)
• 4 star empowerment, 55 (1199)
• faction guardians, 30 (1229)
• affinity bonus, 80 (1309)
• blessing, 75 (1384)
• defiant, unshakeable, and lore of steel masteries, 87 (1471)

total possible resist of 1471 and that's without factoring in unique abilities like mithrala's or situational factors like auras or area bonuses. mind you, this is a theoretical maximum; even in the event that someone managed to gather all the required pieces, no one would build a champ that way because sacrificing all other stats just to stack res would result in an utterly useless champion.

to answer your other question, pct means percentage (or possibly pacific crest national scenic trail. seems unlikely, but this is Trips we're dealing with here and they can be a wee bit odd at times).

so without relic, 1300+ is still possible. That's scary, I was hoping 1200s pre-relic but yeesh. Also I didn't even consider faction guardians lol. What's the 80 "Affinity bonus" one?

I'm assuming Max Res is 20 points higher than max Acc because of Lydia's +100 Arena Res right? Or is there a +100 Arena Acc somewhere?

800 resist?! How is that even possible? When I hear people spout out these ridiculous high endgame numbers I can't help but wonder how it's even possible. Even if every stat on the armor pieces was somehow resist, I feel like that couldn't be done.