Scripts/Icecrown Citadel: Valithria Dreamwalker encounter should start when she is healed and fixed achievement credit

Closes #2117
Closes #2058

src/server/game/Spells/SpellMgr.cpp

@@ -4189,8 +4189,9 @@ void SpellMgr::LoadSpellCustomAttr()
             spellInfo->EffectImplicitTargetB[0] = 0;
             ++count;
             break;
+        case 72706: // Achievement Check (Valithria Dreamwalker)
         case 71357: // Order Whelp
-            spellInfo->EffectRadiusIndex[0] = 22;
+            spellInfo->EffectRadiusIndex[0] = 22;   // 200yd
             ++count;
             break;
         case 70598: // Sindragosa's Fury

src/server/scripts/Northrend/IcecrownCitadel/boss_valithria_dreamwalker.cpp

@@ -355,6 +355,9 @@ class boss_valithria_dreamwalker : public CreatureScript
                     _over75PercentTalkDone = true;
                     Talk(SAY_VALITHRIA_75_PERCENT);
                 }
+                else if (_instance->GetBossState(DATA_VALITHRIA_DREAMWALKER) == NOT_STARTED)
+                    if (Creature* archmage = me->FindNearestCreature(NPC_RISEN_ARCHMAGE, 30.0f))
+                        archmage->AI()->DoZoneInCombat();   // call EnterCombat on one of them, that will make it all start
             }
 
             void DamageTaken(Unit* /*attacker*/, uint32& damage)