[{"name":"Tony","userId":12345,"damage_dealt":[{"character_name":"James","stat_value":100243}]},{"name":"Jimmy","userId":12346,"damage_dealt":[{"character_name":"James","stat_value":1020243}]},{"name":"Tony","userId":12345,"damage_dealt":[{"character_name":"Lebron","stat_value":99900243}]}]

db.collection.aggregate([{"$unwind":"$damage_dealt"},{"$group":{"_id":"$userId","max_stat":{"$max":"$damage_dealt.stat_value"},"damages":{"$push":{name:"$name",damage_value:"$damage_dealt"}}}},{"$project":{"damages":{"$arrayElemAt":[{"$filter":{"input":"$damages","as":"damage","cond":{"$eq":["$$damage.damage_value.stat_value","$max_stat"]}}},0]}}},{"$project":{"character_name":"$damages.damage_value.character_name","stat_value":"$damages.damage_value.stat_value","name":"$damages.name"}},{"$sort":{"stat_value":-1}},{"$limit":30}])