This mechanic is not mine. I found it on a reddit post where u/socialscalie had a rough version on the card for his Wurm tribe. I cleaned it up a bit and here it is. I think it's a really cool form of evasion that green and red could share. This thing gets in one hit and then it can do normal creature things. I'm sure there's a red creature with Burrow and Haste that is going to be awesome.
If anyone has more concise wording for the ability, let me know. I might use this in a future set.