#ci question

The trick here is to just do the math. Let's say you have five mana available as well as seven +1/+1 counters on Animar. That means that we can cast Walking Ballista as though we had 5+7=12 mana available, meaning that X=6.If you want to understand the technical process for what's happening, here's the step by step process: First, choose a value for X. This value gets plugged into both X's in Walking Ballista's mana cost. After you've done that, you take that cost and apply any cost increases or reductions, such as Animar's, to determine your total cost for the spell. Of course, it's a lot easier to do it the other way rather than choosing X before you do the math about what that will make the total.

Delve is one of the few things that can get around Trinisphere's ability. This is because Delve (along with Improvise and Convoke) is a payment mechanic and not a cost-reduction mechanic. The total cost of a spell is determined before any cards are delved away from your graveyard, and so Trinisphere has to just look on in disgust as your opponent casts their Gurmag by paying {B} and exiling six cards from their graveyard.

No. You're out of luck here.Players can never cast spells or activate non-mana abilities while a spell or ability is resolving unless instructed to do so by that spell. A player can only activate mana abilities while a spell or ability is resolving if the resolution of that spell or ability asks for a mana payment from that player. Estrid's ultimate does neither of these things, so all of its effects will happen from start to finish without anyone being able to respond once the Opalescence is milled over by the first part of its resolution.

No, this won't work.Sneak Attack only allows you to put creature cards from your hand onto the battlefield, not creature cards from other zones. Even though Experimental Frenzy is letting you treat the top of your library like it's part of your hand, it's still not part of your hand and thus those cards can't be Sneaked in to attack.

The number of lore counters on a Saga doesn't matter once a chapter trigger is on the stack. That trigger will resolve as normal based on the number of lore counters that were on the Saga when it triggered.Removing the counters from the Saga while the chapter III trigger is on the stack will keep the Saga from being put into its owner's graveyard when the chapter III trigger finishes resolving. At the beginning of your next precombat main phase, you'll add the first lore counter to that Saga again and thus trigger its chapter I ability.

When you're dealing with a complex situation like this, you need to just look at it step by step.As Bioshift resolves, it removes five counters from Toothy and wants to put them onto Fathom Mage. However, Pir's replacement effect steps in and increases that number by one, meaning that Fathom Mage gets six +1/+1 counters put onto it. This triggers Fathom Mage six times.As each of the Fathom Mage triggers resolves, Toothy will trigger. When each of those triggers resolves, Toothy will get two +1/+1 counters: One from the trigger itself and an extra one from Pir's replacement effect.When everything is said and done, you'll have drawn six cards with Fathom Mage, which will have six +1/+1 counters on it, and Toothy will have twelve +1/+1 counters on it in total.