Kretch Butcher is not a difficult superbeing to kill solo if you prepare well beforehand.
Do not fight in block against butcher, he will crit you if you're blocking.
Before fighting Butcher it is important to kill all kretch guards/sentinels in location as if they join butcher fight, he will sacrifice them to gain health. These mobs do not respawn after you kill them.
Level 2-6
In group is easier to have each player drop 3 wraiths and carry one slot scrolls to heal others if needed. just remember butcher has effect that removed heal status effects that he casts randomly around every 4 or 5 minutes.
Possibly will get relict fossil drop for players up to level 6.
Buffs should be any that increase HP or strength like BoV buffs such as Darshana/Loka + warlord/elder. ifIyou use rainbow buff, he will drop Butcher Evil Eye to exchange for QS.
At level 2-6 he has 7864 HP and he can be killed fairly easily with 10 iguarons.
A good belt setup (for level 5+) would be giant + power + 4 heal potions. Use potions instead of scrolls as he has an ability that removes heal effects that occurs randomly.
DO NOT USE ANYTHING HIGHER THAN LEVEL 6 WRAITHS or his HP and strength will jump to the next tier!
Level 7-8
Buffs should be similar to before, any that increase HP/strength like elder/warlord + BoE/BoV buff etc.
Group similar to before, each member drops about 3 wraiths each and possibly has one slot in belt for heal scrolls to help ally if needed.
Same as before, use rainbow buff to get butcher evil eye drop.
At this level he has 14025 HP and is a bit stronger than previous levels.
I personally use the cheap wraiths from fragments like Korr or DH boss wraiths here as they can be bought in auction for 2-5s per fragment and they're stronger than golems and cheaper too, plus they have bonus effects similar to the bosses they're cloned from.
Or alternatively, use about 10 golems, more if you don't have 8 slot belt and blue armour set.
Always clear location mobs before attacking butcher.
DO NOT USE WRAITHS HIGHER THAN LEVEL 8 or his HP and strength will jump again.
Level 10 and above
He has 18138 HP and is stronger than before.
I have no personal experience at this level but the fight will be pretty straight forward.
Use strong buffs and good wraiths here if you don't think you can kill him on your own. gargoyles or legend guardians possibly.
All of these are possible without using mount but I have never personally tried to kill him without wraiths. If there is a way to do it without spending 50g on buffs, I would happily try it out.