note: I have beaten 5 bc 4th trial hitless, but in no way does that mean I am 100% correct, this is what worked for ME. Also, I don't have dlcs yet, so I can't help with dlc bosses, sorry.
##basics:
mutated boss mechanics:
Concierge: doubled and has less health for each clone (1). He also (and most importantly) has no phase changes, he starts in his most threatening form.
Conjunctivitis: starts with max chains, meaning 3 major phase changes, being (in order) a bullet hell at about 90%, the one tentacle phase at about 50%, and another slightly harder bullet hell at about 30%. Another thing is that he will spawn tentacles naturally over time, kill him fast. Another important change is that he will move only one time before attacking you.
Time keeper: main changes is that she is faster, more aggressive, and full heals upon phase change.
Giant: has 4 hands, sounds simple, really sucks. These hands being destroyed won't trigger the eye to pop out, so never focus them.
Hotk: harder summon phases, has 1 new attack that is the later 2 attacks of his 3 hit combo. His spike then jump attack has him jump twice, might catch you off guard. He also won't use the flags attack and can use the super slam early.
tubes:
The tubes are pretty simple, you pick a scroll type at the start, the tubes will only have matching item types (unless naturally colorless) and can only spit out unique stuff per tube.
choice rooms:
There is one at the start, one after level 1, and one after level 2. The one at the start contains 3 colorless items, the 3rd can't be a weapon to my knowledge.
The one after level one is a standard choice room, dame for level 2, unless you are on trials 3 or 4 and hitless'ed the previous level.
boss selection:
There are signs above the door leading to the tubes that have an item on it that relates to the boss it will be. On t2 or 4 there will be 2 and in order from left to right. The selection is random, so even with dlc, it will choose 2 completely random bosses.
custom mode:
This game mode is imbalanced asf and 5bc, hitless t4 is a great example of that. Using custom mode limits variability and allows you to get synergies easier. I was put off at first by it, but after using it for boss rush, I never looked back. I highly, HIGHLY recommend using it.
items:
Items and necklaces scale with you as you progress. Pretty simple, their levels increase when you get more scrolls. Let's move on.
##general advice:
weapon choice:
If you are trying to do hitless, cursed sword, not even a question. If you are just playing to play, avoid biome weapons like sym Lance (unless legendary), tombstone, etc. I would recommend a tactics build for fast kills, but anything works, really. Best weapon is likely bat just for its insane dps and generally easy to get synergy. I'd avoid weapons like twin daggers due to generally mid performance and limited generalization of use.
to parry, or not to parry:
Shields are incredible in the normal game, they are also incredible in boss rush, if not more so. Basically any shield is good, but ramparts is something else, it is the best by far. A nice 2nd place would be Frontline, boosted damage is always nice and can promote a melee heavy style. Anything works, really.
skills and powers:
Depends heavily on your build. Can't really comment much, but stuns and roots are always nice.
backpack:
Pack mutations can cause a nice synergy with some builds. Good example is hokuto's with dot builds. Again, varies a bit too much to really have one solid opinion other than, pack things are good.
mutations:
Again, varies too much for a legit comment.
##t4 5bc hitless strategy:
custom mode:
I had cursed sword as my only weapon, ramparts as my only shield, I had ice armor and diverse deck selected, and finally (and arguably most importantly) Stun nade.
scroll selection:
You might think because cursed sword is in use, that we should use brutality. This is not the case, survival is by far the best for hitless because of the colorless choice room. Select the survival tube to your liking and cursed sword has a very high chance to appear in the choice room (about 80% id say).
loadout per level:
Level one, I like stun nade plus ice armor. Diverse deck works too. Level 2 is double stun nade all the way. Stun plus legendary ice armor works too, but double stun nade is the best due to time keeper's bs. Level 3 is hotk and he can't really get stunned, so double ice armor is the best.
mutations:
This varies heavily on the sword. I will explain further in that section. Generally, master of arms is the most applicable alongside combo. The best, however, is heart of ice due to level 1 and time keeper. Having heart of ice allows you to perma stall both of the twins, allows you to skip the bullet hell phase of conjunc, and alongside MoA, allows you to kill time keeper without her even attacking once.
##da sword:
The funny sword is the main part of hitless. It makes the task of doing it go from impossible to improbable (trust me, big improvement). Knowing how to tech around it is important, and knowing it's strengths and weaknesses can be key. It is so important, in fact, I feel it deserves a section to itself for being an incorrigible ass.
normal affixes:
This is the most important part. Affixes matter a lot, so much, in fact, that it can determine the viability of your run, boss rush and normal game. The best one for overall use in this is the bleed affix due to if being able to work on all bosses unlike the stun affix. This is solely due to open wounds, easily one of the best mutations in this mode for the sole reason of synergy. The next best is stun for somewhat obvious reasons, as mentioned prior; the amount of stunage you do in the first level is crazy, and it makes time keeper pretty much a joke. There are other affixes that are nice, grenade adds to your combo allowing a quicker boost in damage, on fire and poison can be awesome, but bleed is the main one to look for. Luckily, rerolling is worth 200 gold, making looking for something you like very easy. But wait, this is NORMAL affixes, there's more...
THOSE affixes:
There are affixes that increases damage for a tradeoff, you take more. This, however, literally changes nothing when you have the cursed sword. If you see the x2 or x4 affixes, keep them and don't reroll again. The damage is too good to risk.
the argument for legendary sword:
There is a genuine argument for using legendary sword over normal sword, ramparts, and double ice. I personally think both are good because ice and ram limits hotk damage while cursed deals so much that it in turn limits his damage. Use what you think works best.
If you have any questions or think I should go over something more in depth, let me know
Bye bye :)
