$re = '/^(?<id>[^=]+)=(?:<Picture id="(?<picture>[^"]*)"\/?>)?(?<stuff><[^>]*>)?(?<description>.*)/m';
$str = 'STR_ABL_DAMUP_WIND_EXPLAIN=<Picture id="ICN_PRM_007"/>Wind attack power +{Perc}%
STR_ARENA_ENTRY_INFOMATION_PAGE_05=<__>The first time you clear the challenge, you will receive a<__><Color id="Yellow">reward</Color>, so give it your all!
STR_CHAT_VIEWER_TRADE_SPIRITS=You can unlock this chat for {TradeRate} katz spirits.
';
preg_match_all($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