Explain it like I'm 5: Chaplain's Blessing.

One thing I don't think I've seen mentioned is the value of a card. It has the same problem as [[Fog]] except it's actually worse in many cases.

Yes, it's a single mana. Yes, it gains you a non-insignificant amount of life. But the problem is that it doesn't do enough to be worth a card by itself. 5 life won't help you recover if your opponent has a better board state than you. It won't help you push in the final damage if you need to win. It won't affect the board if you're at parity. If you play it on turn one, then you don't feel too bad. But even then you haven't actually done anything to help you win.

In the best general case, it'll buy you a turn, just like fog. But it won't do anything to help you actually win in that one extra turn. Fog at least lets you 'trick' your opponent into swinging out and leaving you open to kill them on the swing back. And even that is incredibly best-case scenario. More often, it'll save you a bit of damage or just sit in your hand.

So why is potentially saving yourself a turn bad? Because imagine that 5 life was, say, a 2/2 for 2. It could block and potentially trade or eat a removal spell and get it out of your opponent's hand. Or it could even do damage and get you closer to winning. It'll actually help you.

Now, keep in mind a couple of things. The effect itself is very powerful. If you had a 2/2 for 2 with "when you cast this spell, you may pay W. If you do, gain five life" that would be a powerful card in at least limited. It's just not worth a card by itself. You can also build decks around lifegain. Likely not anything competitive, and it's almost never going to happen in limited. But you can do it.

/r/magicTCG Thread