$re = '/^if *\(([^}]+)\) { ([^}]+) \}(?: else { ([^}]+) \})? endif$/m';
$str = 'if(stat(life) >= 2) { abc(5) deal_damage(5) } else { gain_block(5) } endif
if(s) { what; } else { asd } endif
if(stat(life) >= 2) { deal_damage(5) } else { gain_block(5) } endif
if (whatever i want) { deal_damage(1) } endif
if( has_status_fx(chill) ) { gain_block(1) } endif
if (true) { deal_damage(5) }
if(false){ gain_block(1) } endif
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php