When it comes to expressing complete amazement or astonishment, the phrase "blow one away" does a pretty good job. However, if you're looking for synonyms to vary your language, there are lots of options available. For example, you could say someone "knocked your socks off," "left you breathless," or "completely astounded" you. Other options might include "impressed beyond words," "totally floored," or "shocked to the core." Additionally, you could say someone "blew your mind," "left you reeling," or "completely bowled you over." Regardless of what phrase you choose, the important thing is to convey just how impressive or surprising something was!