By the way, it seems the Ouroboro of legends that this creature is based off on is generally depicted as a serpent eating its own tail. In other words, this creature's illustration is pretty accurate.
Well, first of all, let's go over the basics.
These are both quite interesting stats. 20ST secretly means that with one friendly territory beside, the ST reaches 30 and forces Mycoron to use items in order to multiply. While limited in use, it definitely has its uses.
Next is 20MHP.This is also very interesting. With 20MHP, it gets destroyed by the simple Magic Bolt. It also is destroyed by area damage spells like Death Cloud and Tempest. 20MHP also means Barrow Wight will accidentally destroy it and be unable to cause Sleep if Ouroboros is not on a Wind territory. 20MHP means that on a +10HP territory like Wind or Multi, Ouroboros will have 30HP in battle and is immune to 30ST attacks that cause ailments, such as Medusa, Werewolf, Cockatrice, Nike, and Wendigo.
When controller has 4 or less territories, upon destruction in battle, revives as "Ouroboros".
In other words, as long as you control 4 or less territories, it can never be destroyed in battle.
However, Forced Teleportation by Little Grey and Forced Transformation will work on Ouroboros and combos like Cockatrice + Battering Ram will destroy Ouroboros as a different creature, so there is no revival.
Scrolls don't really matter, but Items is unfortunate. In other words, you don't get to do Ouroboros + Dynamite, which would result in an ST80 attack + Revival. However, you can use weapons and armors, including Wind Shield to negate creatures like Nike or Cockatrice.
Weapons mean you can use Storm Causer to suicide to avoid creatures like Nike or Cockatrice or the Sleep scroll.
Fairly heavy. The G cost itself isn't high, but you need to discard to summon and you also need a Wind territory.
This is actually a good balance, as the Wind territory requirement prevents any deck from using Ouroborus as a territory holder at the beginning of the game.
Now then, after that analysis, here are some strategies for Ouroboros:
Reasons to use Ouroboros:-Incredible resilience to destruction in battle
And that's it. That's all Ouroboros needs, really.
However, because Ouroboros can only have 4 territories, if you just move and try to reach the goal by moving around the map, you will have a hard time winning, because you can't control as many territories as the other Cepters. So when controlling Ouroboros, you always must try to force your opponent into your high level territories, such as using Holy Word and controlling territories that cannot be avoided.
The main play style is simply to get Ouroboros on the field as quick as possible and level it up as quick as possible. Because Ouroboros does not require territory defenses, you can play him on any territory. In general, you might probably just use Wind territories, because you need at least one to summon it in the first place. But if you place him in Wind territories, he will be prey to Nike and Forced Transformation and Barrow Wight. Placing him on any other territory will make him prey to Elemental Wrath, but it is very rarely used.
Almost any Holy Word works, not just Holy Word 1, but it also depends on the map. For instance, on the map Chain, Holy Word 3 might be a better choice than 1 because you can use it on yourself at the beginning of the game and immediately land on a Wind territory.
Also, Word 2 and 3 are cheaper than 1.
There are generally two choices on spells to cast on Ouroboros-
Land Protection - Once you cast it, it will protect Ouroboros from all of those nasty spells, such as Magic Bolt, Telekinesis, Turn to the Wall, etc. However, Death Cloud, Punisher, Tempest, and other area damage spells will pass through Land Protection. Also, books that focus on map damage will come with Remove Curse, which will also be a problem.
Phantasm - You will be immune to all damage spells, but your opponent can easily overwrite it. Also, Telekinesis and such will still go through, which is a big problem. If you use Phantasm + Invisibility, you can gain perfect defense to spells, but Invisibility can be easily overwritten as well. While rare, Plague + Punisher goes through.
My personal choice is Land Protection. The spells it protects against are far more common than what Phantasm protects against.
-Books with lots of area damage spells that pierce through Land Protection
--Use Mass Phantasm, though then your weakness switches to spells like Turn to the Wall
--What if your opponents have both types? Give up
--Magic Bolt or Evil Blast; even if there is no Basalt Idol, you could use it to take out opposing territories
Other cards that work well with Ouroboros:
Decoy + Life Gem - A self-destruction combo that works unless your opponent has a Scroll. When using Ouroboros, you cannot increase the amount of territories you control, so self-destruction attacks are the only ways to safely defeat opposing territories you land on.
Wraith - Not a combo, but it is a self-destruction attack. However, you only have a 60% chance of killing your opponent's creature.
Also, beware of negation items and Attack First.
Squonk - If you do not want to only take out high level territories, you could use Squonk with creatures like Executor or Nuclear Fusion to take out low level territories. However, it might be more efficient to just put in spells like Haste and focus on increasing the level of your territories instead.
Holy Llama - You will need to use Peace to protect it, but Holy Llama can be used to get your needed Wind territory. After you get that territory, you can cast Peace and then use Llama's Territory Ability to cast Holy Word 6, either on you to avoid territories or your opponent to force them on yours,
It also allows the summoning of Ares.
Late-game, this card's use does decrease, but it still works to force 90G summoning costs on every player.
Wild Growth - If you use once, Ouroboros will at least survive 1 Death Cloud or Tempest; however, if Ouroboros is ever destroyed, since it revives as a new "Ouroboros", it will return to 20MHP
Meteor - Against high level territories
Earth Shaker - Works great with Ouroboros, but does not work on certain territories. However, it can do greater damage than Meteor to overall Magic assets.