The common rule is that once the three kings are set they have 13 moves to win.

Both Gonyaev' Shtyk and Petrov's Triangle work but Petrov's Triangle is easier to remember.

There are three stages:

Stage 1 - take both double lines.

1.cf4

Stage 2 - while on double line take one of tripple lines, this forces the opposing king to leave the other tripple line.

[
6...ba5
7.fd6!
Important! You set two possible heads of the triangle, with next move the third king will move into the remaining "leg" position.

ad8*(*
*7...ae1*
*8.hf6*
*)*
8.hc3
]

ad8

Stage three - set the triangle - it looks like a man with two feet and the head towards the opposing king.

8.fd6

[
8...da5
9.ce1
*(*
*9.db4*
*ad8*
*10.eb6*
*d:a5*
*11.ce1*
*a:c3*
*12.e:a5*
*)*
9...ad8
10.eb6
d:a5
11.db4
a:c3
12.e:a5
]

[
This also wins
9.db4
hd8
*(*
*9...hg3*
*10.ef2*
*g:e1*
*11.ba5*
*e:b4*
*12.a:c3*
*)*
10.eb6
d:a5
11.ce1
a:d2
12.e:c3
]

*
created with Aurora Borealis 3.0*