24 Jan 2020
You can't pay {2}{R} and not sacrifice a nonland permanent, or vice versa. The cost must be paid in full or not at all.
24 Jan 2020
While resolving Dreamshaper Shaman's ability, you can't pay {2}{R} more than once or sacrifice multiple permanents.
24 Jan 2020
If there are no nonland cards remaining in your library, you just randomize your library and continue playing.
24 Jan 2020
Dreamshaper Shaman can be sacrificed to pay for the cost of its own triggered ability.