The Pure Land (Merciless) is an Advent Stage unlocked after clearing River Acheron. It appears on the 11th, 12th, 25th, and 26th of every month. When clearing this stage, there is a chance to unlock Medusa Cat. This is a No Continues stage.
- Black Okame spawns as the boss after 3.3 seconds100f.
- After 13.3 seconds400f, Doge Dark starts spawning every 29.3~32 seconds880~990f.
- After 26.7 seconds800f, 5 Gory Blacks and 3 Ginger Snaches spawn every 58.7~60 seconds1760~1800f and 5.3~8 seconds160~240f, respectively.
- After 86.7 seconds2600f, 3 more Doge Darks spawn, delay 2~4 seconds.
- After 146.7 seconds4400f, 3 more Ginger Snaches spawn, delay 1~3.3 seconds30~100f.
- After 193.3 seconds5800f, 3 more Doge Darks spawn, delay 3.3~6 seconds100~180f.
- After 253.3 seconds7600f, 3 more Ginger Snaches spawn, delay 6.7~9.3 seconds200~280f.
The name of this game is stalling and burst damage. With that 100% Knockback, Okame will have no problem pushing through nearly any unit that stands in its path. Short-ranged, slow attackers are not recommend for the boss, since they'll most likely be beaten into submission with that 800 Omni Strike.
Rushdown units such as Bullet Train Cat, Fishman Cat, Awakened Bahamut Cat and Power Cutter Cat are recommended to slowly chip away at Okame's health. With their high speed, they will also force Okame to stand still, which is important if your strategy is based on stalling Okame.
Keep in mind that the peons that are periodically sent throughout the level. They will have no problem ripping away at your units and tearing a hole in your plan. Units like Pizza Cat and dual Islands can help negate this issue. Don't underestimate your other units as well; Fishman can pull their weight as well. If you absolutely must, try to stack them and kill them all with Awakened Bahamut Cat. Don't rely on this too much, as you may end up wasting time trying to get the enemies to sync, when you could just take them out normally. Stall with Manic Eraser and Roe Cat, keep Okame at bay, be wary of peons, and (hopefully) you'll be able to wear it down enough to deliver the killing blow (Breakerblast does wonders here).
Strategy 1 (Uberless, no Talents)
Bullet Train Cat, Pizza Cat and Power Cutter Cat should be as high-level as possible. Do not replace Pizza with other anti-Blacks unless you have no choice. Roe Cat is fine at level 30.
Keep in mind that this stage is a single boss with periodic and sparse waves of enemies, therefore, as long as you have a way to not let Okame advance despite the other enemies, you will eventually kill it.
Start with Power Cutter for free damage, then let the first Doge Dark get closer and defeat him with Bullet Train, then start summoning Erasers.
The second step is to summon Cyberpunk Cat and start "spamming" Roe Cats for the rest of the fight.
The general idea is that the Roes will stop Okame, Cutter will damage it, Pizza will clear the peons after the defense line breaks, Cyberpunk will limit the pushback and the Breakerblast Cannon will reposition Okame further back after Pizza kills the peons and the defense line is restored.
Your Cyberpunks will die, but you should be able to respawn them often enough to keep up with Okame.
Rinse and repeat 'till you win.
You may not win, in that case, try again while being more careful about this: Always spam Roes. Spam Manic Erasers and Pizza only when peons are coming/present. Save Bullet Train for Doge Darks or Ginger Snaches when no Gory Black is around. Save Cutter for Okame or panic situations. Ramen Cat is there for Combos only. Add Sniper the Cat or give Talents/levels to your units if it's still out of your reach.
Strategy 2 (Featuring Immortal Yukimura)
Lineup*: 2 Unit Defense UP (Sm) combos like Pork on Rice and/or Sportswoman (depending on your levels you may not need both), Maglev Cat (30), Roe Cat (34), Pizza Cat (35), Awakened Bahamut (40), Immortal Yukimura (30), Cyberpunk (38).
Cyberpunk is not required for completion, and can be replaced with combo units in order to form a Defense UP (M) combo. Pizza Cat had a Level 5 Wave Talent unlocked during completion, but this is not required either.
Cannon: Breakerblast (18)
*Levels listed above are the levels used in the attempt, not required levels. This is especially true for Breakerblast Cannon, upgrading it does not increase effect, only ease of use. Although obviously, the higher your levels are the better.
The idea of this strategy is to easily answer every threat with Rusher units until the only peons remaining are sporadic Doge Darks. At this point, the battle is easily won. Because of the level's strict timing on enemy spawns, it is easy to boil it down to a precise science for an almost guaranteed victory, at least provided you own Immortal Yukimura.
Start by upgrading Worker to Level 2. Then start spamming Roe. For the rest of the level, don't stop spamming Roe. When the Doge Dark is halfway to Roe Cat, spawn Maglev. Then spawn Pizza. This start off will buy you as much space as possible to deal with the relatively heavy peon spawns at the beginning of the stage. From this point on, you can spawn cats whenever the necessary criteria occurs.
The criteria is notified here: always spawn Roe Cat no matter what. Spawn Maglev whenever any peon has reached the frontline. Maglev serves as a perfect counter to the single Doge Darks that spawn infinitely throughout the level. Spawn a Pizza Cat whenever a large group of peons spawns. They won't always get many attacks in, but they will deal a lot of damage. You should spawn Immortal Yukimura only whenever a Gory Black reaches the frontline; else, rely on Pizza, as their spawn rates are not even. Immortal Yukimura will one-shot it. Awakened Bahamut Cat is your safety net. If Pizza can't hold back a peon rush, or Immortal Yukimura is offline when a Gory arrives (which he shouldn't ever be) Awakened Bahamut can save you. Spawn Cyberpunk whenever you have a decent amount of cash. Try to keep enough for Yukimura at any given time.
Breakerblast: Use Breakerblast whenever the frontline is close to Okame. For best results, wait for Cyberpunk to slow Okame before firing.
When the Gory spawns stop, you can push whatever Rushers you have at Okame as soon as they come online. Just remember to keep Maglev ready in case a Doge Dark arrives at an inopportune moment. The best time to spawn Rushers is when Roe Cat has weakened Black Okame. This allows them to take another hit, which means their damage output will increase by 50%.