Penguin Tearlament

TLDR: Penguins are a group of Aqua monsters that enable a Spell card that gives you targeted hand discards for effect and also Synchro summon into Muddy Mudragon. Every once in a while, you'll also get to bounce/banish with their effects. 

Penguin engine break down

• Royal Penguin Gardens offers targeted hand discards for effect so long as you have a penguin in hand or on field, it also adds a penguin monster from deck to hand to enable the hand discards. This effect also reduces the level of said penguin monster in hand and on field.
• The Great Emperor Penguin is normal summonable by Gardens effect and summons two penguins from deck, Glacial Beast Polar Penguin and Nopenguin. These cards can be used as material for link summons like I:P or Synchro into Muddy Mudragon. If going second, Polar Penguin also becomes a free targeted banish when special summoned off of Emperor.
• Muddy Mudragon has the same clause on field and in grave as King of the Swamp where it can replace a named material if used for a fusion summon. It also has an effect to fusion summon using cards you control and it's self. Muddy Mudragon + Scheiren on field fuses into Grapha and then Scheiren + Muddy Mudragon in grave fuses into Rulkallos.
• Access into Sprind as either Nopenguin or Polar Penguin both become level 2 with the effect of Garden.
• Penguins are all Aqua, giving consistent access to Kaleido-Heart.
• Polar Penguin is a level 3 Tuner, using Tearlaments Kashtira (Or Danger! Nessie! if you decide to add it) gives access to level 10 Synchro monsters like Baron or Icejade Gymir.
• Sometimes an extra bounce/banish off a Penguin effect comes up and allows you to break a board in ways your opponent did not expect you to. Remember, Nopenguin in grave chain blocks!

An ideal Penguin opener might go something like this:

1. Royal Penguin Garden to search for Emperor
2. Garden effect to reduce the level of Emeror and then pitching Sulliek
3. Sulliek add Scheiren
4. Normal summon Emeror and activate it's effects to summon Polar Penguin and Nopenguin. If the opponent has a targetable monster, you can banish it with the effect of Polar Penguin
5. Synchro into Muddy Mudragon
6. Activate Scheiren effect to summon
7. Muddy Mudragon effect to fuse into Grapha Dragon Overlord of Dark World
8. Since Scheiren has been sent to the grave for effect, activate Scheiren effect and fuse it's self with Muddy Mudragon into Tearlaments Rulkallos

Extra Deck

One of the main advantages of this engine is that it only demands one extra deck slot in Muddy Mudragon, meaning that the extra deck has a lot of room tech cards and/or redundancy.

In my own experience, I have found that two Kaleido-Heart and two Dragos Stapelia greatly improve turns 3 and 4. This allows you to play more recklessly with your fusion summons and frees up Keldo and Mudora effects to shuffle more of your opponent’s cards rather than needing them to recycle your own fusions. Sometimes you also simply do not have Keldo/Mudora anyways and the redundancy can make the difference in those situations.

Considerations specific to this build are:

• If you have or can afford Baron over Icejade Gymir, then do so. That said, Icejade Gymir is not a bad card and does have some applications as protection effect and as a quick effect Ghost Ogre that banishes. Cutting the level 10 Synchros is also not out of the question as they do not come up often.
• Mariness Coral Anemone can be used to special summon Reinoheart who can then send a Tearlament to grave for Rulkallos. You can also special summon Polar Penguin to trigger it's bounce effect, then if Noepenguin is in grave, Nopenguin will chain block the bounce effect and special summon it's self after which, you will then have material to make any Link 2-4, Rank 3, or Level 6 Synchro Water monsters.
• If you insist on playing more Penguin cards, then you can add a single Penguin Soldier or Nightmare Penguin to the main deck to special Summon off a Penguin Brave for a quick effect bounce/banish when your opponent activates a monster effect.
• If you really really insist on playing more penguin cards, then two Penguin Solider in main gives you access to Toadally Awesome, or two Nightmare Penguin in main gives you access to Bahamut Shark into Toadally Awesome off of an Emperor Penguin effect.

Non-Engine

This deck is very engine heavy and so only comfortably fits about 6 non-engine cards in total. For these, Gameciel and Super Polymerization are high value when used and naturally fit into the overall strategy. Since you only have so much room for non-engine, I recommend avoiding low value cards like Ash Blossom or Infinite impermanence as they will often not do enough to get you ahead in a game.

If you wish to add more non-engine cards, or different engine cards like Dangers, I would remove cards in the following order:

1. Trivikama can brick your opening hands.
2. Tearlaments Metanoise is nice to have but not mandatory if it means playing something better.
3. Keldo and or Mudora. As these cards are not required for recycling your fusions, they can put into the side deck and only used for matchups where they matter like Branded.
4. Tearlaments Reinoheart to only 1-2 copies.
5. The Great Emperor Penguin and Nopenguin. The discard engine and access to Sprind will all still work with only one Penguin, but frankly without Muddy Mudragon, there is very little point in the build.

Side Deck

Not much to say regarding the side deck as this is format dependent. For siding however, always side out Emperor Penguin and Nopenguin when going second. The discards will still work with just Polar Penguin and getting to the Muddragon line is unlikely when your opponent has already setup.