Some "LV" monsters automatically "level up" into more powerful cards during the Standby Phase, while others have to fulfill conditions, such as destroying an opponent's monster by battle. Most of the high-end "LV" monsters tend to have extraordinary powerful effects, ranging from the fearsome lockdown of "Horus the Black Flame Dragon LV8" that prevents the opponent from using Spell Cards to the ability of "Armed Dragon LV10" that wipes out many opposing monsters at once. The use of "LV" Monsters in a player's Deck typically grants easy access to something very strong and very quickly without the need to have the stronger monster in the hand first, and grants an additional Deck Thinning effect because of this as well.
Types of "LV" Monsters
All "LV" monsters have a basic setup: A low-Level "base" that has some basic defense that will help it survive until it can level up to the next one, a mid-Level form that acts as the primary monster, and a final, powerful form that has devastating effects and stats. However, there are distinctions between the different sets that sets them apart. Also, in the artwork of the card, the first of the series is usually an "immature" and comical version of the series, with the mid-level being typical of other monsters, while the final one shows something akin to the trump cards of other archetypes.
An exception to the above are the "Armed Dragon" and "Ultimate Insect" series, which both has 2 mid-level forms (however, "Armed Dragon LV7" was originally the trump card of the series, as evident by its lack of an ability to Summon its final form).
The first type of "LV" monsters mimic the "level up" mechanics of RPGs fairly well. The first monsters in each set will also have a fairly easy time leveling up to the next Level (similar to the many "training dungeons" at the beginning of RPGs). The "Silent Magicians" are slightly different-each time a player draws a card, it gets a Spell Counter which gives it a boost of 500 ATK. Once it has 5 Spell Counters, it can be Tributed to Summon its greater form, which has a permanent 3500 ATK and immunity to Spell Cards. However, all of the final forms of these monsters are Nomi monsters, meaning they are unusable unless you have already exhausted all of their previous forms. The advantage to these types are that their mid-level forms can be Normal Summoned without restrictions, making them quite usable in other Decks, not just "LV" Decks. These will also likely be the ones used most during the course of the Duel, due to their usefulness compared to relative ease of Summoning. Note that the mid-forms of these sets are all 1-Tributers, so there is some difficulty in Summoning them normally, giving a reason to use their base forms. The following are all of this type:
- Armed Dragon
- Horus the Black Flame Dragon
- Masked Knight
- Silent Magician
- Silent Swordsman
The second type is exclusive to the "Mystic Swordsman" series. These were perhaps the 'prototypes' for the third type, as each card was theoretically usable, since they could be Set normally (but only the base form could be Normal Summoned). However, due to the low DEF of these cards, they are not likely to survive their first turn, and any protection cards could be better used for other occasions (since these could be Special Summoned easily in a Deck dedicated to them). Apart from this, this type of card has few drawbacks compared to the first type, namely that all three versions could be used with devastating effect regardless of whether or not you plan to Level them (Namely, "Mystic Swordsman LV2" was an improved version of the once popular "Sasuke Samurai"):
The final type are perhaps the easiest to Summon, but hardest to use. This type has no restrictions on Normal Summoning. However, the trade-off is that they only obtain their effects when they are Summoned by their predecessors. This makes it especially hard for the "Allure Queen" and "Dark Lucius" series to level up, as the mid-Level form requires the effect to level up, and the support card "Level Up!" cannot give them their effects, since they are not Summoned by their predecessors. The condition for their effects also makes them especially vulnerable to "Swords of Concealing Light", "Book of Moon", and even "Darkness Approaches", as they will no longer count as being Summoned by the effect of their predecessor. However, their final forms are quite powerful and, with the exception of "Allure Queen", could still be used either for its reduced effect ("Dark Mimic") or simply for its brute strength ("Ultimate Insect" and "Dark Lucius"):
- Allure Queen
- Dark Lucius
- Dark Mimic
- Ultimate Insect
These were only used by Yugi Muto in the manga and the Dawn of the Duel arc of the anime. They traditionally go up a Level every Standby Phase, while gaining 500 ATK. These are anime-only and essentially served as prototypes for the other "LV" Monsters.
The "Winged Kuriboh" series, while technically "LV" monsters, do not follow the normal "LV" system, as they are more akin to upgraded forms (such as "Jinzo" and "Jinzo - Lord"). "Winged Kuriboh LV9" doesn't have any relations to the normal "Winged Kuriboh" and "LV10" whatsoever.
- The 1 Tribute versions of "Horus the Black Flame Dragon", "Silent Swordsman", "Mystic Swordsman", "Masked Knight" and "Ultimate Insect" all have 2300 ATK.
- The "Dark Mimic" series is the only one without a Tribute Monster in its set. Additionally, "Mystic Swordsman" is the only series to have a final form that is a one-Tribute monster.
- The "Ultimate Insect" and "Armed Dragon" series have the most evolutions, but only the "Ultimate Insect" set can Summon its various forms through its predecessor's effect.
- "Silent Swordsman" used to be the rarest of the "LV" monsters; all three of its forms were only Ultra Rare and came from different sets. Its final form was only available as a Limited Edition Promo card. As of Legendary Collection 3: Yugi's World Mega Pack, this is no longer the case, as all three forms of "Silent Swordsman" are now available as Common. They and the "Silent Magician" monsters were also reprinted as a part of Yugi Muto's "Gadget" Deck in Yugi's Legendary Decks, making them all extremely easy to acquire. They were reprinted again along with new support in Duelist Pack: Rivals of the Pharaoh.