Question 1 of 4
What do you do?
While I personally would not Magma Spray if my Goblin Deathraiders were blocked (I'll get to why in a second), the fact is that you incur literally no risk by attacking and have the potential for noticeable rewards by attacking with your trampler before doing anything else.
If my opponent blocks, I would let the two creatures trade and then play a replacement Goblin Deathraiders post-combat.
I make this play because I'd rather have a Magma Spray left in my hand than a Goblin Deathraiders. When I draw another land I'll be able to play Dregscape Zombie and Magma Spray in the same turn. Or I might want to (or have to) wait on using my Magma Spray until my opponent plays a nasty utility creature such as Drumhunter.
If my opponent doesn't block, then we've got a slightly more difficult question on our hands.
We could play a second Goblin Deathraiders. Then if our opponent plays a creature next turn, we'll probably be able to Resounding Thunder it and get in for 6 damage, knocking them down to a precarious 11 life points.
But that only happens if we draw a land.
If we don't draw a land we'll likely end up attacking with both of our Goblin Deathraiders, trading one of them and then having to Magma Spray the Druid of the Anima post-combat to prevent things from getting out of control (or to keep it from just trading with Goblin Deathraiders the following turn, which would be an option that your opponent would likely follow if he or she did not have impressive mana-hungry plays to make).
The other option is that we can Magma Spray the Elf post-combat. While we waste a mana to make this play, it immediately takes away a mana source from our opponent, thus equalizing whatever apparent disadvantage we might normally incur when we make plays that do not maximize our mana.
If my opponent does not block, I would Magma Spray the Druid of the Anima post-combat. I do this because it is both a more desirable play to make if things do not go according to plan over the next couple of turns and because our opponent might be in desperate need of that mana.
There are some true nightmare situations that can occur when your opponent has four (plus) mana sources to your two. And there are plenty of situations where your opponent literally will be unable to cast spells for a turn (or more) if you eliminate a mana source.
However this is not a strictly dominant play* as we do give up some of the best-case scenarios that we could get with two Goblin Deathraiders in play and some good removal in our hand, but those situations are not easy to come by.
*In Game Theory, dominance occurs when one strategy/play is better than another strategy/play for one player, no matter how or what that player's opponents may play.
Question 2 of 4
What do you do?
Like in the last question, the very first thing we should do is attack with our Goblin Deathraiders, because we give up nothing to do so.
Like last time, I'd prefer to have the Magma Spray in my hand than a Goblin Deathraiders. If we make this play then next turn we will be able to play Kathari Bomber or Goblin Deathraiders and still have mana to play Magma Spray. (I'd make my decision of whether to play the Kathari Bomber or the Goblin Deathraiders based on whether or not I drew a land. If I drew a land I'd cast the Kathari Bombers first, as that would allow me to cast Goblin Deathraiders and Dark Temper on the subsequent turn.)
Unlike last time, we already have all the pieces we need for the best-case scenarios to take place. Not only are the best-case scenarios more likely to occur, they're better than they would have been in the previous question.
In this case, we give our opponent an extra mana to use on his or her next turn, but in doing so we are able to utilize all of our mana this turn and on our next turn.
Question 3 of 4
What do you do?
Well, the first thing to notice is that unlike in the previous two scenarios it is not completely free to attack with your creature before making any other plays. It is conceivable that you might want to Magma Spray the Druid of the Anima precombat in order to get through for two damage with your Dregscape Zombie.
Another thing you might think to yourself in a situation such as this one is "Well, there's no way that I'm going to let the Druid of the Anima live through this turn, so I'm going to Magma Spray it before combat and attack with my 2/1."
While that might sound like a reasonable thought process, it actually is not.
If you attack, your opponent could very easily decide to block (in fact, the entire reason to Magma Spray precombat is based on the assumption that your opponent might block). And blocking also leads to a dead Druid of the Anima.
Now, I don't believe that the Druid of the Anima has to die here.
Getting back from these thought process questions, the first thing that I will do is to attack with my Dregscape Zombie.
The reasoning for this is exactly the same as in the last question.
While it does not actually affect my play decisions, it is important to pay attention to when you can do something completely for free. Sometimes the best way to improve your ability to spot strictly dominant plays is to contrast them with similarly appealing, but not completely dominant plays.
Question 4 of 4
It's Round 1, Game 1. It's the beginning of your second turn and your board consists of Veinfire Borderpost.
What do you do?
If we had a Mountain to replace one of the Swamps it might be a different story as I could then cast a Goblin Deathraiders this turn, and on the following turn I could Magma Spray the Druid of the Anima and play Goblin Outlander.
But as it is, I'm just not prepared to leave my opponent with four mana against my two.
As it is, by playing Magma Spray now, next turn I'll be able to cast Kathari Bomber and by the turn after that I'll probably have drawn something impressive that I will want to cast, or I will have drawn a Mountain to allow me to cast both of the gold two-drops that are currently littering my hand.
By casting Magma Spray here, the one mana that we are "wasting" gets paid back to us as our opponent will be down a mana source. In fact, this play saves us a lot of mana because we will either end up Magma Spraying on our following turn (which could leave us down as much as two mana) or we will end up allowing our opponent's Druid of the Anima to live even longer, producing more and more mana for our opponent and causing us a bigger and bigger net mana loss.
The Common Thread
All these questions ask us to find the best way that we can use our mana. And that's what your early-game decisions are almost all going to be about. Always think about what your mana can do for you. Sometimes you have a series of very excellent, nearly scripted plays, as we do in questions 2 and 3. Other times you are in undesirable spots where you need to figure out the best way to avoid falling behind, as we are in questions 1 and 4.
At times you will have to make plays that does not allow you to maximize your mana, and that's OK. It's especially OK if giving up a bit of mana efficiency on one turn allows you to truly maximize your mana (and prevent greater inefficiency) on a subsequent turn.
Just because there is less on the board than there will be later in the game doesn't mean that your plays are any less important. Your first couple of turns can make or break your game, if you use your cards to the best of their ability, then you will have a very strong foundation from which to build the rest of your game from.
It's 6 p.m. on Tuesday. You are at your local card shop and they couldn't quite get enough people to fill the sanctioned draft that you wanted to play in. Seven people—so close!
When they find out that the draft won't be sanctioned, some people begin playtesting Standard for the upcoming PTQ. But there are three other people at the store that still want to draft.
You aren't going home tonight without casting some spells.
What do you do?