Heh. Took me quite a while to figure this out... but yeah. As of this revision, the change is at line 445 in status.c.

git-svn-id: https://svn.code.sf.net/p/rathena/svn/trunk@5670 54d463be-8e91-2dee-dedb-b68131a5f0ec

Changelog-Trunk.txt

@@ -5,6 +5,8 @@ IF YOU HAVE A WORKING AND TESTED BUGFIX PUT IT INTO STABLE AS WELL AS TRUNK.  EV
 GOES INTO TRUNK AND WILL BE MERGED INTO STABLE BY VALARIS AND WIZPUTER. -- VALARIS
 
 2006/03/18
+	* Fixed BA_DISSONANCE and DC_UGLYDANCE not working. status_check_skilluse was blocking
+	  them due to the lack of an exception like BA_MUSICALSTRIKE has it. [blackhole89]
 	* Documentation update on NPC whisper and rid2name. [Lance]
 	* Fixed event_kill_pc to behave like what it should instead of another replication
 	  of event_death. Added script function rid2name to convert bl ids to name. [Lance]

src/map/status.c

@@ -441,7 +441,8 @@ int status_check_skilluse(struct block_list *src, struct block_list *target, int
 			if (sc->data[SC_DANCING].timer != -1)
 			{
 				if (skill_num != BD_ADAPTATION && skill_num != CG_LONGINGFREEDOM
-					&& skill_num != BA_MUSICALSTRIKE && skill_num != DC_THROWARROW)
+					&& skill_num != BA_MUSICALSTRIKE && skill_num != DC_THROWARROW
+					&& skill_num != BA_DISSONANCE && skill_num != DC_UGLYDANCE)	//[blackhole89] - these hit even (only, in fact) if you are dancing too
 					return 0;
 				if (sc->data[SC_DANCING].val1 == CG_HERMODE && skill_num == BD_ADAPTATION)
 					return 0;	//Can't amp out of Wand of Hermode :/ [Skotlex]