No idea on where the numbers came from.

I just auto generated the character and then looked at the power cards and set them to show personalized data.
Yeah, I'd have to check on it, but I think something might be broken with recuperating strike's calculations in that example...
At 21st, it should be 2[w]+
2d6+Str+stuff - still high, but remember this is a striker, so it should be high. At 21st level, a ranger with twin strike will be doing 2[w]+3d8+stuff, followed by 2[w]+stuff. And a rogue would do 2[w]+dex+cha+stuff+5d8 with combat advantage.
It's in-line with other strikers, IMHO. It's a little lower on damage, but it gives you temp HPs and you don't need to set up special conditions first.
edit: Also, I noticed that Tide of Blood is a level 7 encounter power. By 21st level, at-wills will often far overshadow low-level encounter powers. I'd have traded that one away by now, but I don't know if the auto-builder can cope with those sorts of vagaries.
What's more, it didn't explain Tide of Blood quite right. You get +1 to damage
per enemy within your CON modifier squares, not adjacent. So, within a 13x13 square if your CON modifier is +6. This could potentially be a LOT.
-O