The lack of any reasonable solution is a good evidence that this mobs shouldn't be there. I don't follow people who propose such mobs into the TI, as it is causes grievances to so many other players. The usual response "you should learn how to play RO" is getting old; a truly competent RO players who knows the game well would be able to see that this mobs are not fit for level 126-141 in places like high TI.
Nevertheless, I found that you can finish this TI by using some gimmicks and teamwork, after 6 completed 400 counts. There are no good strategy that will easily beat this TI without a wipe. It is usually about 3-4 wipes per each 400 counts from my experience, which is awful for a well coordinate and well geared team of players.
General Guidelines:
1- Do not recruit squishy classes that cannot wear a shield (Ranger, GX). They are liability and will likely get your party wiped. 1 or 2 Ranger would be a maximum but not recommended at all. They die too often to everything and it is more of a burden to AB than the DPS benefits they provided.
2 - General party composition would be:
1-3 Sorc
2-3 Full Support AB
2-4 DB RK with 120 DEX wearing Temporal DEX boot.
1 Stringer
1 Wandy
0-1 Cart Cannon Gene (Pick Gene over Ranger)
1 Sura
You can get by with the minimum number required and still have 3-4 spot available. You can recruit any classe that are not squishy and can wear a shield. They will require to have a spellbreaker accessory and Yggdrasil Leafs. RG Sacrifice is not required and you will probably want an extra hand to cast spell break (which RG can also do).
3 - Getting into entrance.
1 - Send one person on a suicide mission at the entrance to scout for opportunity to get in. 4+ KK is generally a NO NO and should wait for KK mobs to die down before attempting.
2 - All of the RK should go in first, DB the mobs, and Bwing back to safety. Repeat until the mobs are cleared, then everybody go in at once. You can send Sura to tank the mob, and follow up with RK, which works as well given Sura are able to cast MS in time.
4 - General Tactics around KK
1 - Main Sorc is dedicated to cast and recast magnetic earth, and perform the usual SP battery role. ME should be recast immediately once KK breaks a hole in it. Your party lives count on it. Expect 300-400 yellow/blue gems for a 400 counts of TI.
2 - String and Wandy are doing Magic String and Gypsy Kiss with other fancy buff like Dance with Warg and Frigg Song.
3 - RK are main DPS, and they should stay within Magnetic Earth and spamming Dragon Breath / Water Dragon Breath under String. Brynhild / Cranial Strong shield is highly recommended. It is better to die on the spot and be revived than to take less damage but fly 20 miles away, resulting in a search and rescue mission to find your positionally bugged corpse.
4 - Geneticist should use Ghost property cannon for extra DPS.
5 - Sura is there to be a pinball for KK. Leading the party and taking any JT hit. Brynhild is recommended to fix the annoying positional bug. If you cannot move, it usually means your character is somewhere else and you need to click at various random location on a screen to restore the correct position.
6 - DO NOT engage more than 3 KK at once. 4+ KK will result in a casualty and 6+ KK is generally a wipe. This duty is up to Sura to warn the rest of the team of potential danger. Sometimes you may run into the 7+ KK or it spawn next to you, and there is little you can do but to wipe and start over. Very frustrating.
7 - Gwing is generally a suicide.
8 - AB is doing the usual AB role. Unbinding praefatio is a good idea. All attacks are magic and assumptio is preferred. Stay inside Wandy and spam col. to keep everybody HP full is not a bad strategy.
9 - The rest of the class in the party and spare sorc have one role. Spam Spell break on the KK. This works surprisingly well if you engage UP TO 3 KK at a time.
10 - Unfrozen Wind armor + Cranial shield are probably the best, but will not save your life. Nidhogger Shadowgarb, KBC Accessory, and Glorious Ring comes very handy for survivability.