RG Live WotLK 3.3.5a

well the player casts the stun on itself, same goes for the creaturesummon

case EVENT_FROST_TOMB:
                    if (Unit* target = SelectTarget(SELECT_TARGET_RANDOM, 0, 100, true, -SPELL_FROST_TOMB))
                    {
                        Talk(SAY_FROST_TOMB);
                        Talk(SAY_FROST_TOMB_EMOTE, target);

                        DoCast(target, SPELL_FROST_TOMB_STUN, true);
                        // checked from sniffs - the player casts the spell
                        target->CastSpell(target, SPELL_FROST_TOMB_SUMMON, true);
                    }
                    events.ScheduleEvent(EVENT_FROST_TOMB, urand(14, 19)*IN_MILLISECONDS);
                    break;

soo i vote it was a tmporary bug of something - cannot reproduce https://youtu.be/y2Cvvs7bAMs (video from livewotlkrealm)