User blog comment:Sam Wang/BTD5 - Tips For Reaching High Rounds/@comment-3153244-20120808070404/@comment-3153244-20120808105247

I'm not saying to avoid using RoDs completely, just that they haven't been as effective since their pierce was lowered from infinite to 100, although they're still powerful (just expensive). A guide for high rounds is here, although not 100% of the information may be up to date.