Supernatural abilites

[Irk]

I had a few questions about these.

1. The first: apart from extend supernatural ability, is there any other similar effect, like a persist Su or something?

2. what are the best supernatural abilities?

If you guys have other questions, feel free to ask them, even though this is a pretty specific topic.

[BowStreetRunner]

Tome of Magic has both Extend Supernatural Ability and Empower Supernatural Ability.

Many of my favorite supernatural abilities would not really benefit from either Extend or Empower, as they are active all the time and don't have numerical effects. I would include Hide in Plain Sight, Divine Grace, Turn Undead, Wild Shape, Imbue Item, and Mind Blade.

I also like the feat Supernatural Transformation which allows you to transform one of your Spell-Like Abilities into a Supernatural Ability.

[Psyren]

The best ones are the ones that mimic spells, because they do so without XP costs, M/S/V components, and even AoOs. For example, a Zodar's Wish is totally free.