why not use X + up AND USE HOLY LIGHTINIG

that with damged

hit this head to make him avoid usese his powerful attack

Dullahan HP 600 his weaker to ice attacks

before you get in were it is heal your self then get in,he will use it's special attack
click down button,attack it's eye or attack any part of it's body (only the shown parts)
while attacking doge it's attacks too.

I kno who your talking about, and yes it can be hard at first, but he only uses 4 attacks
anyway. the first one where he slashes you, i believe ducking down is the best option,
when he causes these spikes to come up at you, i think either jump high enuf to keep out
of the way, or slide under him (its been a while and my memory is all rusty) when he sends
lots of blobs out with his head, duck and slide like mad (a left right left right at the
right intervals is often the best) and as soon as he finished that just try nd not get hit
with 2 many of those little squigly things. Hope i helped :)