Each power-up ability is an activated ability that can be activated only once. You'll put one or more +1/+1 counters on the creature. These serve as a handy reminder that you activated the power-up ability. There may also be other effects, some of them quite devastating. If the creature enters and you activate the power-up ability all in the same turn, you get a discount on the power-up activation. That activation cost will be reduced by the creature's mana cost.

Plan is a new enchantment subtype found on a group of enchantments that, appropriately enough, lay out a plan for you. Each has a triggered ability that tells you what action you need to take to advance the plan. This triggered ability will put a plan counter on the enchantment and give you a minor reward as it resolves. A second ability will reward you for bringing the Plan to fruition, triggering when a certain plan counter is put on the enchantment. For Doom Reigns Supreme, that's the fifth plan counter. As that triggered ability resolves, you'll sacrifice the Plan and unlock your ultimate reward.

Previous Magic sets have included double-faced cards that required you to play them with their front faces up and transform them in some way to get to the back faces. The Zendikar Rising set features an exciting new take on this concept with modal double-faced cards: they don't transform, but instead you can play either face right away!