Is Sunburst optional

[Gambit]

If there is a trinisphere in play and they want to play Engineered explosives for zero but are forced to use colored mana to play the explosives does it trigger the sunburst? Say they tap 1 island and 2 mishra's factories, how many counters does the EE come into play with? Hope that was clear.

[Dark_Shakuras]

It would come into play with 1.

U(1)(1) was payed. U = 1 counter.

However if you wanted to play EE for 2 with a 3sphere out, and you only had (lets say) Island, Plains, Forest out (and no other lands) you would not be able to.

As it comes into play, Sunburst looks to see the mana spent on it. It doesn't care why the mana was spent, only what color it was. Thus your EE would be a 3 counter EE.

Same for Sphere of Resistance/Thorn.

[cdr]

Sunburst: Sunburst is a static ability that functions as an object is coming into play from the stack. "Sunburst" means "If this object is coming into play from the stack as a creature, it comes into play with a +1/+1 counter on it for each color of mana used to pay its cost. If this object is coming into play from the stack and isn't coming into play as a creature, it comes into play with a charge counter on it for each color of mana used to pay its cost." See rule 502.37, "Sunburst."

Sunburst says "cost", which is anything you had to pay in order to play the spell - whether that's X, an additional cost, or even Trinisphere.

[Gambit]

thanks folks