var questTemplates =
    from quest in db.QuestTemplates
    where q.MinLevel <= wowMain.Me.Level + 2
    where (q.SpecialFlags == 0 || q.SpecialFlags == 4)
    where q.SuggestedPlayers <= 1
    where q.RequiredMaxRepFaction == 0
    where q.RequiredMinRepFaction == 0
    where q.RepObjectiveFaction == 0
    where q.LimitTime == 0
    where q.ReqSourceID1 == 0
    where q.ReqSpellCast1 == 0;

var _startEntry = quest => db.CreatureQuestRelations.FirstOrDefault(a => a.Quest == quest.Entry);
var _endEntry = quest => db.CreatureQuestRelations.FirstOrDefault(a => a.Quest == quest.Entry);

var _start = startEntry => db.CreatureTemplates.FirstOrDefault(x => x.Entry == startEntry.ID);
var _end = endEntry => db.CreatureTemplates.FirstOrDefault(x => x.Entry == endEntry.ID);

var _creatureStart = start => db.Creatures.FirstOrDefault(x => x.ID == start.Entry);
var _creatureEnd = end => db.Creatures.FirstOrDefault(x => x.ID == end.Entry);

var _mapStart = creatureStart => creatureStart.Map == wowMain.Me.MapId;
var _mapEnd = creatureEnd => creatureEnd.Map == wowMain.Me.MapId;

var quests =
    from quest in questTemplates
    let creatureStart = _creatureStart(_start(_startEntry(quest)))
    let creatureEnd = _creatureEnd(_end(_endEntry(quest)))
    select DBQuest
    {
        Quest = quest,
        CreatureStart = _mapStart(creatureStart) ? creatureStart : null,
        CreatureEnd = _mapEnd(creatureEnd) ? creatureEnd : null
    }