burntgerbil said:
The Divine Oracle lvl 20 power (p73) has been the wildest I've seen. On a miss, it rewinds time back to right before you used the power and lets you choose another action instead.
I think you are quite missing the point.
How do you narrate that? Easy.
"You look into the future and see yourself miss, time rewinds back to right before you use the power. Now you can try something different."
Ok, that's slightly tongue and cheek and I'm sure I could think of something more exciting if I tried, but the point is that if the power is explicitly magical then it simply does what it says it does with no extra explanation needed. Magic means, 'No realistic explanation is needed'.
A power is only difficult to narrate if you insist on seeing the 'martial' power source as meaning 'not magical'. If you insist on this, you end up with all sorts of twisted situations trying to explain what happens in ways that don't appeal to 'magic'. But, if you simply accept that 'martial' power sources are just different sorts of magic, all the problems of narration go away.
This is why I've had such a good chuckle at the expense of all those that praise 4e for allowing them to run 'low magic campaigns', because they could limit the available classes to those with 'martial' power sources. Well, sure, but on close inspection doing so doesn't in fact get the magic out. Heck, it doesn't even get the flashier magic out. It just limits you to the sorts of magic martial artists in Eastern martial arts fantasies tend to have. That is different, but hardly 'low magic'.