DemonstrateDemonstrate is a triggered ability. “Demonstrate” means “When you cast this spell, you may copy it and you may choose new targets for the copy. If you copy the spell, choose an opponent. That player copies the spell and may choose new targets for that copy.” (CR 702.144) (When you
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) this spell, you may copy it. If you do, choose an opponent to also copy it.)
Choose two basic land types.
CreateTo create one or more tokens with certain characteristics, put the specified number of tokens with the specified characteristics onto the battlefield.
If a replacement effect applies to a token being created, that effect applies before considering any continuous effects that will modify the characteristics of that token. If a replacement effect applies to a token entering the battlefield, that effect applies after considering any continuous effects that will modify the characteristics of that token.
Previously, an effect that created tokens instructed a player to “put [those tokens] onto the battlefield.” Cards that were printed with that text have received errata in the Oracle card reference so they now “create” those tokens. (CR 701.7) the appropriate Shockland token. (For example, if you choose Island and Swamp, you'd get a Watery Grave token.)