Hello everyone and welcome to my 191st analysis, this time featuring Nadiel the Flooder.
Overview: Flooder is one of the saddest monsters in the game. His best role is only available once he is at least Rank 3, nobody will try to obtain him when compared to the other Nemeses, and he is slow by today's standards for a denier. Unlike his other forms, he can't apply great Tortures or remove buffs either, so he's stuck with Guard Down, Total Damage Reduction, debuff removal and Freeze, and only the last part is unique to Flooder. His trait is great though, and among Nature monsters he's notable, so there's that I guess.

Builds:
Monsters that have access to Group 4 skills will have a slightly different build path. I will list the most viable builds for each Rank since some moves in Group 4 are pivotal to some sets' success. The monster's role will likely remain the same, however, so this won't be exhaustingly long as I won't repeat the same things.

Rank 0:
Moves:
-Endangered Ecosystem
-Druzhby
-Monona
-Nature Pact
Runes: 3 Team Speed
Mutant Rune options: Team Speed&Team Life
Relics: Staves and Masks

Build Explanation:
Endangered Ecosystem removes all debuffs from all allies and heals them by 30%, but its CD is high so use it carefully. Druzhby and Monona are single target Freeze moves and Nature Pact is an AOE Total Damage Reduction, and these give Flooder the necessary tools to protect his allies.
3 Team Speed with Team Life Mutations are the standard for supports.

Rank 1: Flooder learns "Protect Ecosystem" at this level, a Base 40 unresisted AOE that gives all enemies Total Damage Reduction.
Moves:
-Endangered Ecosystem
-Druzhby
-Protect Ecosystem
-Nature Pact
Runes and Mutant Rune options are the same as given above.

Build Explanation:
Protect Ecosystem is Nature Pact but it deals damage, and it replaces Monona for this reason to give enemies another turn of Total Damage Reduction.

Rank 2: Flooder learns "Pack Nature Pact" at this level, a Base 40 Nature AOE that gives all enemies Guard Down.
Moves:
-Endangered Ecosystem
-Druzhby
-Protect Ecosystem
-Nature Pact/Pack Nature Pact
Runes and Mutant Rune options are the same as given above.

Build Explanation:
If you feel like Protect Ecosystem is enough, you can get Pack Nature Pact over Nature Pact to give all enemies Guard Down and make your allies' attacks land regardless of Precision modifiers.

Rank 3: Flooder learns "Paterswoldse" at this level, a Base 40 Water AOE that Freezes all enemies.
Moves:
-Endangered Ecosystem
-Druzhby
-Protect Ecosystem
-Paterswoldse
Runes: Same as above but 3 Speed is now an option
Mutant Rune options: Same as above but Speed&Life is now an option

Build Explanation:
With this, Flooder can become a denier, and let me remind you once again that this is the most impactful move that's unique to Flooder - except for Druzhby, Monona and Paterswoldse, ALL other options are shared between all Nadiel forms. Basically, if you're really desperate for a Nature denier, have a ridiculous number of Nature cells lying around and for some reason have missed all of Talika Cells Monsterwood events, then and only then can actively trying to obtain Nadiel the Flooder (specifically) be pardonable.
3 Speed with Life Mutations are a standard on deniers.

Teammate options: For Teammate options, check out this article.

Countering Nadiel the Flooder: For Counter options, check out this article.