remove death1 ref to core

spells/Death1.tex

@@ -18,8 +18,7 @@
   {The caster's strange stare moves the target into a state of semi-life.
   This grants \gls{dr} 1}% Description
   {
-    The target no longer bleeds or feels much irritation from pain.%
-    \exRef{core}{Core Rules}{stackingarmour}
+    The target no longer bleeds or feels much irritation from pain.
     The spell wears off after \arabic{spellPlusOne}~\glspl{interval}.}
 
 \spell{Sloth}% Name