Two things that came up today

[mattdeballer]

I have two questions that arose today just playtesting with friends at our local store, getting ready for a tournament this weekend. There were two things that arose that we weren't totally sure about, so I am asking here for clarification, so that I know what happens if they come up in the future. My questions are:
1. How does sphere of resistance affect X spells like repeal and skeletal scrying?
2. How does trinisphere affect spells remove from game by Mind's Desire?

Any help is appreciated. We had tenative ruling, but definite rulings would be great. Thank you for looking.

[Dante]

For #1, yes, it adds 1 to the mana cost of all spells.  So if you want to play Fireball and have X=4 (for damage) you would have to pay R4+1 = R5.

For #2, SCG's "ask the judge" comes up with this

Q: Does Sphere of Resistance's effect also work against Mind's Desire? Does my opponent have to pay an additional one for Desired spell?

A: Yes. You still have to pay any additional costs to play the spell. Mind's Desire only pays the mana cost.

[Matt]

In other words, Repeal now costs {1}{U}. It doesn't change what is, so you can still Repeal a Mox - the extra mana from Sphere of Resistance isn't applied towards X.

[Apollyon]

How to play spells:
1) Announce and reveal spell. Put it onto the stack.
2) Choose modes and announce choices for things, such as kicker, entwine, and the value of X.
3) Choose targets (if applicable).
4) Choose additional targets from modal choices, such as kicker (if applicable).
5) Choose how to divide the effects (if applicable). All targets must get at least one of whatever is being divided. You can't target 4 creatures with Arc Lightning and deal 0 to one of them, for example.
6) Determine costs. Include all cost modifiers.
7 & 8) Make mana and pay for the spell.

You choose the value of X before you calculate the costs. So if you want to Repeal a Mox, step by step:
1) Announce Repeal and put it onto the stack.
2) Choose X to be 0.
3) Choose the Mox.
4) n/a
5) n/a
6) U + 0 (from X) + 1 (from Sphere of Resistance)
7 & 8) Pay for it.

The same thing applies to Grand Arbiter Augustin IV, Defense Grid, the Tempest Medallions, Helm of Awakening, and anything else that I missed. Trinisphere is an exception to that. It checks after the cost for step 6 is determined and makes you pay additional mana if the cost of step 6 is less than 3.

Trinisphere's text simplies to: "If this is untapped, nothing that says 'play' can cost less than 3. Ever."

Force of Will costs 3. Spells revealed with Mind's Desire cost 3. Isochron Scepter copies cost 3 (in addition to the 2 that it costs to use the Scepter's ability).

Note that spells that are put onto the stack or into play don't cost a minimum of 3, as you aren't playing them.

[Komatteru]

Neat/notable exception: Engineered Explosives

With EE, what you actually set X at is irrelevant.  When it comes into play, the Sunburst mechanic will look only at what colors of mana you paid to play the thing.  Thus, if SoR is in play, you want to officially set X at one less than you want the number of counters to be.  For instance, if you want two counters, you should set X at 1, then it will cost you 2 mana to play it, so as long as you use two different colors, you'll get 2 counters.

While this is pretty technical, at high REL events, some people might want to know what X is set at, so be careful with that.

Note that having SoR (or Trinisphere, or other cost increasor) in play is the only way to get any counters at all if you flip EE up off Mind's Desire.

[Matt]

Thus, if SoR is in play, you want to officially set X at one less than you want the number of counters to be.  For instance, if you want two counters, you should set X at 1, then it will cost you 2 mana to play it, so as long as you use two different colors, you'll get 2 counters.

Unless, of course, you're using colorless mana to pay for it!