come hell or high water; no matter what happens
A dramatic idiomatic expression meaning 'no matter what obstacles arise'. Literally 'even if rain or spears should fall'. Often used to express unwavering determination.
See also: 雨が降ろうと槍が降ろうと
雨が降ろうが槍が降ろうが、明日の試合には必ず出る。
Come hell or high water, I'll definitely participate in tomorrow's match.
No matter what happens, we will carry out this plan.