Balancing Homebrews

[Zethus]

I've been thinking of extending the Waterborne Adventures Unearthed Arcana via Homebrews and I got to thinking about how people check and balance their Homebrews. How do you balance yours?

Additionally, is this minor Homebrew balanced? (this is me checking)

New Totem Warrior Path

Totem Spirit
Shark - While raging, you can breathe underwater, have a swim speed equal to twice normal speed and have advantage on attack rolls to hit any creature below half of their maximum hit points. The creature must be able to bleed and you must be able to smell in order for this effect to activate.

Aspect of the Beast
Shark - You can smell blood from up to a mile away and can breathe and smell underwater. Additionally, you can track any living creature underwater by scent.

Totemic Attunement
Shark - If you move 20 feet in a straight line, then attack a creature with two or more weapon attacks, the creature must make a Strength or Dexterity saving throw or be grappled. You can also end this grapple immediately to deal 1d8 Slashing damage.

[Oramac]

Typically you're better served to post homebrew questions in the homebrew forum.

That said, your Shark totem looks ok. In a land campaign it's totally irrelevant, but in a waterborne campaign it would be incredibly powerful.

The water breathing on Totem and Aspect are redundant, and I'd make the swim speed from the Totem equal to your walking speed instead of double.

Also keep in mind that most weapons perform at disadvantage under water.

[Falcon X]

Here are some from the Middle Finger of Vecna:

Path of the Fin Berserker, for when you want something like a Shark totem, but a bit more intense: http://www.middlefingerofvecna.com/2016/01/path-of-fin.html

Lizardfolk Race, they may be swamp dwellers, but their swim speed gives them a place in waterborne choices: http://www.middlefingerofvecna.com/2015/10/lizardfolk.html

Pugilist, not waterborne, but as said above, sometimes weapons don't work as well underwater, so fists are better: http://www.middlefingerofvecna.com/2015/12/pugilist.html