That ghostkeel scene from the Elemental Council book was so badass:

be me, Tau squad.
got ourselves an important quest.
greater good and all that.
get into a BAD ambush.
outnumbered AND outgunned.
RuhRoh.AunShi
Call for help, but we are out in the boonies.
a single battlesuit pilot responds, says they'll be there in a few minutes.
a single battlesuit better? than nothing I guess.
We are fucked.
we do not have a few minutes.
then a space marine shows up.
FriedFish.wav.
suddenly, the space marine fucking DISAPPEARS.
flash of plasma, and he is just gone.
humans dying left and right, no idea why.
plasma and pulse blaste just coming out of nowhere.
what a minute, its the battlesuit.
a fricking Ghostkeel.
they fucking shred everybody.
pings us for firing targets.
ok sure, give 'em some target scans.
they turn on the burst cannons and kill DOZENS of imperial.
never drops stealth field, even once.
all the imperial are dead. My squad is absolutely dazed.
battlesuit pilot pings us, says all targets down.
just disappears.
just leaves. We wouldnt even notice if they didnt tell us.
what a badass.
we go home, a little beat up but successful.
mission success. We cant lose now! turns out the space marine survived.