Greven's Rating system:
5.0: First pick no matter what. I will always play this card.
4.5: Splashable and first pick worthy.
4.0: First pick pack 1.
3.5: Early pick though not always a first pick.
3.0: Solid early/mid pick.
2.5: Solid pick in color.
2.0: Should generally make the deck if in this color.
1.5: Decent filler.
1.0: 23rd card if you have to.
0.5: This card will sometimes be sideboarded in.
0.0: I will never put this card into my deck (main deck or after sideboarding).

Is this playable or not?? It a blue ally, so meh. It's a piker , so meh. It's not colorless. I guess -- is the activated ability worth it?
I guess it's a 1.5, but is it a closer to 1 or closer to 2?

2. You're probably going to have a 7 power creature in your deck to make the ability worth it.

1.5

It's not very good until pretty late, and even then...

~SE++

2.0

Playable both early and late. It already won me a game, unblockably attacking for lethal together with some fliers. Many decks in this format will play 18 lands, five mana will be available sooner rather than later.

2.0

Trading with a Scion sucks, but you need early interaction, or you're going to be run over by Gnarlids. The ability is actually good late in the game.

Lost to this last night! Of course, without him activating the merfolk I was just chumping an 8/9 lifelinker, so...