Ok, three things to discuss: Boar VS oread, signaling, and just how good can oppressive rays be, anyway? EDIT: WALL OF TEXT INCOMING!
Firstly, boar. Yes, in the abstract, boar is about as good as or slightly better than oread. In a format where all that triggered oread in the average deck was itself, then it's a beater that probably gains about half a card when you play it. Which is good, mind you, but probably the mostly unblockable boar is better.
in a format where you can easily be playing 8 to 10 enchantments (and JJJ you can potentially do better), Oread is going to gain you about half a card every other turn once you play it, which takes it from "ok" to "bonkers". It makes blocking a nightmare decision for your opponent, it shoots them, and it has a sizeable front to beat them with.
The other factor that makes it better than boars *here* is that it's 1P1P, which means you have a pretty good opportunity to build around it, putting it into that bonkers range. If it's pack 3 pick 1, even if I'm in red I might take the boar; boar is super solid and you'd always play it in red, and on occasion oread isn't going to pan out. But if I've got another 41 picks to make my oread work? It's going to be pretty damn good more often than not. Boar is a card to play because I'm in red; Oread is a reason to BE in red.
Also, the temple of epiphany is so close to completely irrelevant to the discussion it might as well be blank.
But wait, you say - I'm sending mixed signals!
Well, yes and no. Yes, the player next to you is likely to take the magma spray, and if not, the next player is sure to do so.
But no, it's almost never relevant. Sure, if you're in the top 8 of a PTQ it is important to be able to read signals. But you can't read signals off the first two picks anyway!
Lets imagine you get passed this pack, but without a rare in it. What does that tell you about the colour of card your opponent took?
The correct answer is "nearly nothing". It could have been a godsend or dawnbringer charioteer. It could have been a prophetic flamespeaker (or whatever it is called). If what they took was an uncommon, it still doesn't tell you very much.
Worse, even if you can work out what they took, they might not have any idea about signals. Or they might, but then get passed something from the other side they think is a signal. Plus, most players - even quite good ones - are so bad at reading signals that it's almost irrelevant. What you GET passed you should consider the signal - what you PASS is (while not worthless) not very interesting. We can pass the pack hoping to send signal we're not in red, but we've no certainty they are not in white.
Plus, passing left, you are in the drivers seat for 3 packs - sure, you can push them into offering the sweet hookup in pack two, but this is actualy able to be done in a surprisingly small percentage of cases with most players.
Signalling is something to consider. And if the two cards you are looking at are very similar in power level, it's even sometimes worth doing.
In this case, the power levels sure aren't very close.
SO on to oppressive rays.
Removal is good. No question. The question is: How good is THIS removal?
It certainly doesn't "add to your board". It takes away a blocker, but often only for 1 or 2 turns, and past about turn 5, doesn't even reliably do that. If the game does go long, there is a 100% chance that they will be able to re-claim the lost card, even if only as a chump blocker. It even makes the game harder for you to read - are the leaving the mana up to pay for a blocker, or for a surprise flyer with deathtouch?
We're pretty much agreed it is only good in fairly aggressive decks. And by fairly agressive, we mean very very agressive.
Problem is that your format isn't actually that aggressive at all. You've got 1 good aggressive 1 drop (scarhide; the hopolite is a bit of a bother to get to a decent size) and it isn't on colour. You've got 2 on colour common agro 2 drops, with exactly 1 more at common in each colour that isn't blue. (and only 4 more between the colours at uncommon, and that is assuming you count the sub-par sightless brawler). 3 drops have a few more, but hardly any really strong aggressive drops - best of breed are probably linebreaker and oakheart dryads, if you have triggers for the former or enchantments for the latter.
So our pool of cards that go in a hyper-aggressive deck is not super deep. And for this to be a good pick, we've got to at least have a reasonable chance to be a very, very aggressive deck...and it's just not there, or not at the kind of odds I'd like. Yes, there is a fair chance you'll play the card if you draft it, but rays is also the sort of card I'd cut from a fair portion of white decks. I cannot imagine cutting the forgeborn.
Frankly, in my view, Forgeborn is probably in the top 5 or 6 red cards in the set, or very close to that line. Oppressive rays probably isn't in the top 5 white commons.