Effects with multiple parts

Sometimes effects (usually spells or abilities) do more than one thing. The rule for this situation is that those things are done in the order they are listed in the card (rather than, for example, being done simultaneously.) In the vast majority of cases this is inconsequential, but there are a few rare cases where this causes rather interesting effects.

As an example, assume that there's an Elvish Champion and a Civic Wayfinder on the board.

As you may notice, the Elvish Champion boosts other Elf creatures (thus making the Civic Wayfinder a 3/3.)

Now someone casts Solar Tide and pays its entwine cost.

Because the entwine cost has been paid, both effects in the card will happen, ie. it will destroy all creatures with power 2 or less and all creatures with power 3 or greater. So what happens in this case?

Many players will hastily think that it simply destroys all creatures and that's it. However, as noted, if an effect has more than one part, they have to be evaluated in order. This particular situation requires a bit more analysis.

The first part of the spell, ie. "destroy all creatures with power 2 or less" is done first. The power of Elvish Champion is 2, and therefore it's destroyed. Civic Wayfinder is not destroyed yet because its power is 3.

As you may know, or remember from my previous blog posts, a destruction effect takes place immediately. It immediately puts the destroyed permanent into its owner's graveyard (unless some other effect interferes, such as the permanent being indestructible.) Therefore Elvish Champion leaves the battlefield when the first part of Solar Tide is performed.

Now the second part is performed. What happens? A bit surprisingly, Civic Wayfinder is not destroyed. This is because at this point Elvish Champion has left the battlefield and is not boosting Civic Wayfinder anymore, and thus the latter is now a 2/2.

Thus Civic Wayfinder survives the Solar Tide, even though at first it looks like it destroys all creatures.