How to unlock challenges 8 and 11?

[sePL80]

Hello fellow basement dwellers,
I am enjoying Binding of isaac without using guides because I am afraid of spoilers etc.
or..let´s just say I like to keep things mysterious.

So far I have unlocked all challenges except 8 and 11.
Would anyone be so kind to tell me how to unlock them?
Thank you in advance,
sePL

[Nazemec]

8: Become Guppy.
11: Kill Lokii and beat challenge 19.

[sePL80]

Thanks for the quick reply.
So with 11 I see, haven´t finished 19 yet.
But 8 I do not really understand.
How do I become the Guppy?
or if you mean by "become Guppy" to "get Guppy", how do I get the Guppy.
Thank you in advance,
sePL

[Nazemec]

Originally posted by sePL80:

How do I become the Guppy?

It's a transformation. Get 3 Guppy items during the same run (the black cat).

[sePL80]

Thank you!