Spiritual Fire Art - Kurenai is a trap card that lets you tribute a FIRE monster of yours to turn its original ATK into burn damage to your opponent. Since FIRE monsters can have LP-decreasing effects (probably more so than any other attribute), this is a key card in burn decks and decks that utilize strong FIRE monsters.
I refer to cards like Kurenai as "fail-safe" cards. This means that, if something were to be destroyed, this kind of card can be chained to prevent a net loss. For example, imagine someone using Dark Hole on a field loaded with FIRE monsters like multiple Solar Flare Dragons (each must be the last Pyro to be attacked, two or more means they can't be attacked). This can be chained to get rid of one of the Solar Flare Dragons yourself (since you were going to lose them all anyway) and cause some extra damage to your opponent. It can also be a fail-safe for itself (meaning it can chain to its own destruction if you happen to have a FIRE monster out that you don't care for). The most promising use for this is as a Final Turn push. If you win the game, you don't care if you still have all of your monsters. Therefore, if the opponent's LP are lower than the ATK of a FIRE monster you control, use this to give it up for that last bit of damage you need to secure the win.
Strategies and game play:
Some FIRE monsters have skills that allow them to be Special Summoned from the hand or otherwise be quickly brought to the field. Those make good targets for this card's cost, as their summon was fast and (theoretically) repeatable. Xyz monsters also make good targets, as they typically have high attack and cannot use their effects without Xyz material (therefore an Xyz monster with no material can be tributed without losing a usable skill). Alternatively, some archetypes are made up entirely of FIRE monsters, making any monster capable of both archetypal synergy and Fire Art compatability. These archetypes include Jurrac, Evol, Fire Fist, Hazy, Fire King, Battlin' Boxer, the Horus series, and especially Volcanic and Flamvell (both of which contain burn effects).
Combos with other cards:
Some Xyz monsters that can be used with this card are Volcasaurus (2500 ATK and can detach an Xyz material to destroy a monster AND burn for that monster's original ATK) and Coach King Giantrainer (2800 ATK and can use all of his Xyz material in one turn to draw three cards, reveal them, and cause 800 damage per monster he reveals). Giantrainer can also use Rank-Up Magic Barian's Force (preferably after using his skill) to become CXyz Coach Lord Ultimatrainer (3800 ATK and can detach an Xyz material once a turn to try that skill once more. This combo allows for four draws, four chances to burn away 800 LP, and a surefire shot at burning away 3800 LP. Another useful card is Megamorph. The original ATK of the tributed monster comes out of your opponent's LP, but cards like Megamorph can double that original ATK if your LP are lower than your opponent. If you run HERO units that happen to be FIRE, this can be a decent side deck, as it can for an Evolzar deck. A few more specific cards that make nice targets are Jurrac Meteor and Black Rose Dragon (both of which perform a Field Nuke when played), Gaia Soul the Combustible Collective (who gets destroyed by his own effect at the end of the turn anyway), Lava Golem (if you can take it back from your opponent after giving it to them), Koa'ki Meiru Valafar (if you can't pay his Iron Core maintenance cost for the turn), Meteor Black Dragon (who despite having no effect manages a bulky 3500 ATK), Yamata Dragon and Hino-Kagu-Tsuchi (who return to the hand at the end of every turn), a monster(s) who would be destroyed by the effect of Bonfire Colossus or Goka, the Pyre of Malice (or Bonfire and Goka themselves, as they're fairly strong), Dragonic Knight (a 2800 ATK monster that can be Special Summoned by paying a cost of all targeted card(s) that would be destroyed by an opponent's monster effect), and Red Dragon Ninja (who can be quickly summoned with Ninjitsu Art cards and has only one effect, which gets used automatically upon summon).
Ways to counteract it:
Prevent FIRE monsters from being played. Don't use things like the Trap Hole series; those cards require the monster exist on the field (meaning the FIRE monster can still pay Fire Art's cost). Solemn Judgment/Warning work better, but cost a lot of LP (and Judgment would be more practically spent preventing Fire Art, as the cost of tributing a FIRE isn't negated). Alternatively, make sure that you can survive the trap by having more LP than it can burn away. If you survive Fire Art (or any kind of burn card), you usually still have all of your resources (monsters, traps, cards in hand, enough LP to stay alive). Exceptions exist, like things that burn and do other stuff, but that's the weakness of most types of burn card. Additionally, this burn card requires a cost of a FIRE monster. If you can exploit the opponent suddenly having one less monster, you can win in a situation where you might not have won otherwise.
This can burn away the last bit of your opponent's LP so long as you have a FIRE monster that you're willing to tribute. It can be chained to its own or that FIRE monster's destruction (with rare exceptions like Night Shot and Jinzo), and it can be chained to anything your opponent tries to do when their LP gets low enough to suffer a fatal loss. It is certainly a staple in burn decks.
Burn decks, or as I call them: "Get Rich Slowly Over A Lifetime Of Hard Work scheme" decks, are long-term decks and exist in a metagame favoring a short-term playstyle of definitively squashing the opponent on the first turn by assembling a group of unstoppable monsters as soon and as often as possible (HEROs, Hieratic, Rabbitzar, etc). Their main flaw is that, for the ones that can deal out significant damage quickly, there is usually a cost that can be exploited on the following turn by an opponent who would rather use thirty effects a turn to make a gauntlet of bigger sticks to hit you with.
Spiritual Fire Art - Kurenai debuted in Cybernetic Revolution as a common. It was reprinted in Dark Revelation Volume 4, again as a common. It was reprinted again in a structure deck as a common. The card art has no variations.
Artwork and aesthetics:
Like the other Spiritual Art cards, Fire Art Kurenai features a Charmer (in this case, Hiita) in a circle while a large kanji is present in the background. It fits the Spiritual Art theme, and the general theme of FIRE monsters up to the point of its release (high power and/or burn damage).
A failsafe that can produce victory deserves to be rated high, but since it provides no advantage to you if it fails to win and since the current meta has a massive hate for the type of play that would allow for the gradual lowering of LP required to make this a victory card I must reluctantly rate this card four out of ten: awesome to unleash but just not that practical.