no holds barred

no holds barred (without any rules or constraints, especially those of fair play) — 1. все захваты разрешены (борьба); 2. все средства хороши

see also
[the end justifies the means]
[all's fair in love and war]

[stop at nothing]
[go to great lengths]
[по головам]

[for love or money]
[by hook or by crook]
[by fair means or foul ]
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From all-in wrestling of the most primitive kind, in which no hold or grip or indeed any method of dealing with an opponent was forbidden.