Either of those ways you've done it should work.
@if@[@rand@[1|2]||1||You Win!||You Lose!] @rand@[1|2]@rand@ will give the same number regardless of how many times it's used in a command unless the unique option is used with it so it makes it ideal to test. The following relates to the quick test I did
15:30 dante557: !testingtest
15:30 dante557bot: You Win! 1
15:30 dante557: !testingtest
15:30 dante557bot: You Lose! 2
@if@[>||@rand@[1|2]||1||You win!||You die!] Would spit out "You Win!" if the number rand gives is greater then 1 (in this case, 2) and will say "You die!" otherwise.
15:37 dante557: !testingtest
15:37 dante557bot: You win! 2
15:38 dante557: !testingtest
15:38 dante557bot: You die! 1
@if@ and @rand@ are also VIP exclusive variables. If you aren't VIP currently that would explain why you're currently having difficulty getting it to work.
Thanks,
Dante557