Porphyry Nodes

Enchantment, W (1)
At the beginning of your upkeep, destroy the creature with the least power. It can't be regenerated. If two or more creatures are tied for least power, you choose one of them.
When there are no creatures in play, sacrifice Porphyry Nodes.¹
Illus. Alan Pollack

Crystal Keep Rulings Summaries

• The effect is not targeted, so it can choose creatures that say they cannot be targeted. [Planar Chaos FAQ 2006/12/13]
• If there are multiple creatures tied for least power and some but not all of them are indestructible, the indestructible ones cannot be chosen. [Planar Chaos FAQ 2006/12/13]
• If all the creatures with the least power are indestructible, the ability does nothing. [Planar Chaos FAQ 2006/12/13]

Format Legality	Legal in Vintage, Legacy, Extended Banned in Standard
Printings (1/9)	Planar Chaos (Rare)