Tidewater minion, Aphetto alchemist

[Offler]

Can be their own ability used to untap themselves?

example:
I tap Aphetto alchemist to activate its ability.
I choose to untap creature and target the ability onto Tapped Aphetto alchemist
The Alchemist will untap...

Does it works?

[anonymos]

Yes, it can be used to untap itself.

Their ability would not work if it required them to untap target tapped creature because they would then be illegal targets initially.

I'd post where in the rules, but my brain is still kind of fuzzy from a midnight worldwake event.