There will be some thoughts, suggestions and math for self-sufficient warforged builds.
Basics.
There no way to get a lot of repair amplification: 40 racial, 10/20 mists set, up to 70 from gear, 20 construct exemplar epic feat. Up to 50 if artificer and 20 for legendary feat that you'll probably avoid.
Yet unlike heal spell reconstruct is taking full spellpower
and can be empowered and maximazed.
The very core spell in any self sufficient build for reaper epics and higher heroics is reconstruct. Even at 50 rep amp and 100 repair spellpower at 12 it will repair you for 360 outside reaper. And in actually good build you'll have 1,5-2 times better numbers.
Classes with reconstruct are sorc (12) wiz (11), artificer (15) artificer SLA (4)
Most obvious choice is artificer, pure, either melee, evocator or repeater shooter.
Investing in RMM tree 23/26 points will make you literally unkillable on lower skulls.
At 20 as arti you may have around 140 repair amp (40 racial, 50rmm, 10 mists, 40 item) and 250-350 repair spellpower depending on build. With 300 average its 1440 reconstruct self and
1800 maximized same sla. At 20. Even after reaper penalities its enough to outrepair any damage you take in lower skulls.
Wizard or sorc. Wizard is better choice for splash and for repairs overall just imo. You can use lower level repair spells and replace them with buffs at will, you have more spell slots and getting them faster, 3 metamagic feats for quicken and extend at least.
Sorc is much better pure or 2-3 lvls of pally splash. There is a big dillema though: as pure sorc you will want to use savant capstone and loose ability to repair self (you still can toggle off, reconstruct and toggle on). If pally splash you will loose clvls, DCs and sp. Not saying warforged have bad cha by default...
Right now I'm running meleeing ftr/wizard splash. 12 wizard (reconstruct, tenser, gh, yet gh can be scrolled so 11 enough) 8 fighter (needed to take gr weapon focus, yet for kensai t5 and crit profile 6 is enough).
At 20 I had 83 repair amplification (40 racial, 10 mists, 33 heroic heartwood) + 50 on drinking any potion (kensei t4 enchantment); 240 repair spellpower (cc gloves + ship + skill, no implement on weapon). Self reconstruct outside reaper was 746 and 950 after drinking potion. Pure sorcerer or spellcasting wizard will have better numbers yet way less tankiness overall of corse.
Reconstruct scrolls and W&S mastery.
Scrolls have same base clvl of 11 as heal scrolls. Meaning outside w&s mastery and with 100 repair amplification they will repair you for 220. If rank 3 w&s mastery its 385. Artificers are way better here too, cause of in increasing clvl and better repair amp: with 150 amplification its gonna be incredible 656, which is alike healing scrolls over very good healamp.
Arcane spell failure. Besides reconstruct is artificer spell too, both scroll and wizard/sorc spell versions have somatic component and depend on ASF. Base body of wf/bf has 5% asf, mithral 15% and adamantine 35%.
There are some easy ways to reduse asf though: wf racial tree -15%, battle engeneer cores up to -30%, rmm t5 removes asf from armor/docent at all, saphire of spell agility -5/10/15% (mlvl 12/16/20), eldrich knight trees up to -50 total from armor (shitty trees though, I'd never go pass 2nd core).
Adamantine body getting buffed by 12 extra prr in racial tree and extra bonuses in renegade mastermaker. Mithral body is good choice if you have evasion, yet terrible for dodge.
Fast Q&A:
-why not just take healer friend and dont bother?
-cause its boring way. You can convert weakness of the race (50-80% healing from positive) to strong part of being self-sufficient.
-who the fuck play wf nowdays?
-someone who is doing racials or just wanna extra melee power and 20 prr

-you've forgot bladeforged!
-no I'm not. Since they have racial reconstruct scaling with character level... Well its like regular race with heal SLA lol. Literally anything will work till you build something totally retarded.