Does Corsair need to hp wash? I know that it's better to keep low HP but I'm worried that I won't be able to do bossing with him later. And if yes, how much INT i will need, when to stop washing and which method to use?
I washed my corsair slightly, I am at lvl 137 with 5.6k HP. However, in order to fight horntail effectively and not worrying about dying, you would need ~9k of HP. I don't think I am able to achieve that. However, it really depends what your goal is in terms of bossing and what not. Any higher level corsair out there that could shine some lights on us? To whether it is needed to wash to 9k HP without the need for HB? or wash to 7.1k HP with HB?
Reaching roughly 9k HP will help you at Horntail - it's hard to survive in HT without 9k, although it is possible. With HP under 9k, you'd have to rely on HB for all runs, which is a pain (I speak from experience). Having high HP isn't much a problem; at places such as Zak, you can just set your pet autopot so that you only heal up to about 4~5k HP. This way, even if you have 9k HP, 1/1s will only deal 4~5k dmg to your boat (or you could just dismount). Provided that the formulas I found in Gossamer's notes are correct, and provided that you have average luck, to reach 9k HP by Level 155, you'd need to create about 2560 extra MP. If you could have these equips by Level 50: Spoiler: Int equips Zhelm: 25 int Face: 5 int Eye: 5 int Ear: 9 int Pendant: 5 int Overall: 20 int Glove: 10 int Cape: 10 int Shoe: 3 int Wand: 6 int Shield: 12 int and wear them each time you level up from 50 to 155, you'd have generated an extra 1155 MP. All the equips I've listed are pretty average int equips, and all of them (except the Zak helm and the pendant, unless you have a Spiegelmann's Necklace) are obtainable before you hit Level 50. By reaching 100 total base int by Level 50, you'd be able to get another extra 1155 MP between Level 50 and 155. This is assuming you have MW20, which would effectively make your base int 110. In total, having 110 int in equips and 110 base int will allow you to generate 2310 MP from Lvl 50 to 155, and the remaining 250 MP would be fairly easy to generate between Levels 10 and 50. This way, you can reach 9k HP by 155 without too much trouble. My calculations were done under the assumption that you will be getting 20 HP per wash. You'll want to wash using non-fresh AP in order to do this. Useful links that explain how to wash from non-fresh AP and on how to calculate your min MP: HP Washing guide Min MP