My first competitive deck I built was faeries, during Lorwyn and it was a lot of fun. I wanted to build something similar for modern but more robust against the many control decks I had at my local game store. Blue white spirits is my attempt at that fun loving interactive deck.
Blue White spirits is slower at ending games than many of its competitor decks, but it is difficult for your opponent to interact with even post sideboard. Below are short descriptors of each card in the deck:
One Drops:
Mausoleum Wanderer: A underrated spirit that hits hard and controls games. It is an extremely versatile creature that can consistently hit for 2 or more in this deck, and has the ability to counter an instant/sorcery will help protect the rest of the team or stop your opponent from stabilizing with Anger of the Gods, Goryo's Vegenace, Carthatic Reunion, Kolaghan's Command, Scapeshift, Living End, Cryptic Command, Into the Breach and so on.
Aether Vial: A powerful artifact that allows you to go out of the gates much faster than would be normally possible, allowing it to even stabilize in the face of burn. Against control it allows for play uncounterable spirits speed. It is at three because the deck still wants lands for cryptic command, and the second aether vial is signficantly worse than the first to the point of almost being a dead card.
Opt: This deck likes playing on the opponent's turn and as such opt is a nice way to make the deck more consistent at finding the right answers.
Path to Exile: The premium removal of white, it gets rid goblin guides, tarmogoyf, knight of the reliquary, phyrexian obliterator, reality smasher, wurmcoil engines, and much more.
Two Drops:
Rattle Chains: Having a flash 2/1 flying creature come into play at the end of your opponent's turn is great. Having the rest of your spirit team coming in on your opponent's turn is great. Having it come hexproofing the target of their Kolghan's command and causing it to fizzle is just awesome.
Selfless Spirit: Having a maindeck 2/1 flyer that negates the main way deck plan to interact with your spirit ball/ protect your more important spirits is pretty awesome for a two drop. Having that happen at instant speed in response to a supreme verdict is even better.
Phantasmal Image: Copying Drogksoll captain can be game ending against midrange or control, and when playing against a deck trying to get value with things such as dark confidant, snapcaster, or tireless tracker it is amusing to do the same. However I play a two of because there are a lot of matchups where it doesn't do a whole lot.
Anafenza, Kin-Tree Spirit: After experimenting I found this card to shore up a lot of early game weakness. It is effectively a two mana lord that makes the rest of your threats hit much harder. Additionally it can get some of our guys out the range of gutshot, bolt, whipflare, electroylze, and kolaghan's command which is quite helpful.
Azorius Charm: A weird card, but bear with me. It's three modes makes you very flexible game one to whatever threat you are dealing with, and then can be sided out games 2 or three. Against aggro you can give your team lifelink which might be the ticket to stabilzing you. Against mid range you can place their tarmogoyf or other big threats on top of their deck. Finally against control you can use it as a Cantrip to find one of your many spirits that ruin their day.
Three Drops:
Drogskoll Captain: Drogskoll Captain is one of the best lords. He comes into play as a 2/2 flyer while granting your team +1/1 and hexproof. That hexproof could be on your Kira, Spell Queller, or even better yet another Drogskoll Captain. He will likely make your board hard to deal with while granting you the extra power to end the game quickly. Against control it is usually the right move to play him in response to a removal either by vial or rattlechains as he give you some free card advantage as well.
Spell Queller: Without his spirit buddies Spell Queller has seen some play as a nice tempo card for control. In this deck, they are most likely never seeing that card again. Even nicer is that card could be the Supreme Verdict they were banking on wiping your board with.
Kira, Great Glass Spinner: Kira, Great Glass Spinner is the absolute most obnoxious card for your opponent to see if they had any hopes of removing your creatures. If they are lucky they might be able to spend a few pieces of removal, else wise their removal will soon be all dead.
Detention Sphere: Solid removal for planeswalkers, tokens, or other hard to deal with permanently.
Four Drops:
Cryptic Command: Helps you control their board while keeping your card advantage.
If you end up playing a similar brew, I hope you enjoy it as much as I have. I would focus on tuning the sideboard as it can still use work as well as the mana base.