原文You can tap any untapped Myr you control as the last ability resolves, not just the Myr tokens you created with the first ability. This includes Myr that haven't been under your control since your most recent turn began.
原文As the last ability resolves, you can tap untapped Myr you control even if Myr Battlesphere is no longer on the battlefield by then. If that has happened, Myr Battlesphere won't be able to get the +X/+0 bonus, but it will still deal X damage to the appropriate player or planeswalker.