Missing part of the previous commit.

src/server/scripts/Northrend/Nexus/Nexus/boss_keristrasza.cpp

@@ -240,6 +240,7 @@ class spell_intense_cold : public SpellScriptLoader
                 if (aurEff->GetBase()->GetStackAmount() < 2)
                     return;
                 Unit* caster = GetCaster();
+                //TODO: the caster should be boss but not the player
                 if (!caster || !caster->GetAI())
                     return;
                 caster->GetAI()->SetGUID(GetTarget()->GetGUID(), DATA_INTENSE_COLD);

src/server/scripts/Spells/spell_dk.cpp

@@ -168,6 +168,8 @@ class spell_dk_anti_magic_zone : public SpellScriptLoader
                 SpellInfo const* talentSpell = sSpellMgr->GetSpellInfo(DK_SPELL_ANTI_MAGIC_SHELL_TALENT);
                 amount = talentSpell->Effects[EFFECT_0].CalcValue(GetCaster());
                 Unit* caster = GetCaster();
+                if(!caster)
+                    return;
                 if(Player* player = caster->ToPlayer())
                      amount += int32(2 * player->GetTotalAttackPowerValue(BASE_ATTACK));
             }