Spirit monster

Spirit Monsters, originally as a rule, could not be Special Summoned, and are sent back to the owner's hand during the End Phase of the turn they are Normal Summoned, Flip Summoned, or flipped face-up. This also happens if they wound up in the opponent's hand via effects like "Exchange". However, new Spirits have been released in The Duelist Genesis, one of which can be Special Summoned for a cost.

Spirit Monster Cards are designated by having "Spirit" in the place where "Effect" would be. They are also the first secondary type of Effect monsters to have this indicator (the Flip Effect Monsters prior to them simply had "FLIP:" at the beginning of their effects).

Many of the Spirit Monsters' designs were based on icons from Japanese mythology and they all have very similar backgrounds, supposedly of the spirit world. Their OCG names would be given in kanji, but the furigana would be given in katakana which normally would indicate a foreign-language word.

One Spirit monster in particular, "Yata-Garasu", is infamous for its complete lockdown of the opponent's hand when combined with "Chaos Emperor Dragon - Envoy of the End", and is believed to be one of the two cards responsible for the forbidden list.

Play Style
Spirit monsters can only remain on the field temporarily (unless Set face-down), and thus their controllers run into a major problem of maintaining field presence, but many Spirit monsters have devastating special effects to make up for this deficiency. "Mirror of Yata" and "Izanagi" keep the spirits on the field permanently or until they are removed, making these cards a must for any spirit deck.

In addition, there is a loophole with spirit monsters that lets them stay on the field regardless of their return-to-owner's hand effect. The exact text on Spirit Monster cards states they must return to their owner's hand "during the End Phase of the turn [they are] Normal Summoned or flipped face-up". Therefore, if they stay on the field for more than one turn you don't have to worry about them returning to your hand. For instance, a "Hino-Kagu-Tsuchi" monster equipped with "Mirror of Yata" who then had its Mirror destroyed (e.g. by "Heavy Storm" or "Mystical Space Typhoon") would stay on the field the subsequent turns. Another card that can help bypass the common effect of Spirit monsters that returns them to the hand is "Future Visions". When Spirit monsters are Normal Summoned, and afterwards removed from play by the card, the End Phase would have already passed when they return, so they can no longer return to the hand.

Two of the strongest Spirit Monsters ("Hino-Kagu-Tsuchi" and "Yamata Dragon") focus on maintaining a significant hand advantage over the opponent, and when combined with "Spiritual Energy Settle Machine" or other effects like "Dimensionhole" that allow them to remain on the field, they can easily turn the tide of any duel in their owner's favor. Though it wasn't an option in the past, there is currently enough support for decks entirely themed around Spirit monsters to be viable. Because Spirit monsters return to the player's hand, the player runs the risk of having too many cards during the End Phase, forcing a discard, so "Infinite Cards" is an effective way to counter this problem. Cards like "Exchange", "Creature Swap", and "Mystic Box" are staples.

A commonly used card with Spirits is "Mausoleum of the Emperor", which allows users to pay a life point cost to get high-level Spirit monsters out without tribute. Trap Monsters are also often used either as tributes or as a method of maintaining a field defense when the Spirits leave the field.

Their effects range from Beatdown, Direct Attack, hand control, and even field control, making a dedicated spirit deck very flexible regardless of what the opponent has. However, due to their habit of returning to the hand, cards that make you discard will be a serious hamper, as Spirit Monsters in general are rather useless in the Graveyard. Cards that recover discarded cards are thus suggested, but not recommended as Spirit Monsters do not have much in the way of deck thinning. Once the problem of field presence is resolved, spirit monsters can be quite annoying as well as devastating, since it is hard for the opponent to destroy them, and even with cards that forces discards, it is hard to target a particular spirit monster (unless something like "Card Destruction" is used). This is particularly true for "Inaba White Rabbit", as it can attack directly while avoiding opponents' counter-attacks, making it quite annoying as well as devastating.
 * See also Card Rulings:Spirits