Roshi typically run +HP unless your have a massive pow advantage. Without HP mood (or a big pow advantage, roshi has severe trouble surviving past round 1 or start of round 2.

If you do have a big pow advantage over your opponent, then +NIN mood to do extra dmg is a decent choice.

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-Nin is very unappealing for roshi because you really would wish his damage stack up faster most of the time; -nin does not help in that regard.

-Def makes roshi a bit more vulnerable, but is not game breaking. There are times where you'd wish roshi is just a little bulkier to survive that extra round.

-Attack slightly reduces roshi's mystery and standard attack dmg, but not by much. You'll regret not killing off a 50 hp ninja once in a blue moon.

In the end you are stuck picking -attack or -def, both have advantages/disadvantages. If your roshi is in a fast team such as hidan team, I'd run -def. If your roshi is in a slow team like han team, I'd run -attack.

65% def mooded roshi on a HP tile can easily die round 1 to any form of lighting blitz, be it the old mb blitz or newer cloud blitz, due to those teams having mostly tai/nin mixed attacks. He also dies to mabui 1010 on round 1 if a standard attack combo go off on him thanks to all the tai/nin mix attacks and pure nin attacks he receive. This kind of roshi is almost certainly dead at start of round 2 if facing an opposing hidan roshi team; while a hp mooded one will survive comfortably.

HP mood is there so that your roshi do survive to round 2, where he can break potential barrier and take significantly less damage in return, or receive healing/shielding support from your team. 65% hp let him eat quite a bit more hits than 65% def in early rounds. Def mood only works well against pure tai attacks.. which is not that common, as most high damaging attacks in round 1/2 are tain/nin mixed or pure nin.

I'd say, even if you are using earth main, you are still better off running HP mood (and sitting in a +HP tactics tile). Almost all relevant threats to roshi use tai/nin mixed attacks or pure nin attacks, rendering +def a lot less effective. Even with earth main, if you mooded HP, your roshi would come out with more hp left in most cases. If your roshi dies, he died to nin dmg or tai/nin mixed dmg. Pure tai damage would not kill him without a massive pow gap even without extra def.

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If you really desperately want def, go sit in a +def tactics tile, and still run hp mood. That get you more hp and def th*ing def mood on a hp tile for roshi.