Hollowsage — ruling 1

If Hollowsage becomes untapped during your untap step, the ability will trigger. However, since no player gets priority during the untap step, it waits to be put on the stack until your upkeep starts. At that time, all your “beginning of upkeep” triggers will also trigger. You can put them and Hollowsage’s trigger on the stack in any order.

Hollowsage : règles, fonctionnement et interactions (MTG)

Hollowsage is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Whenever this creature becomes untapped, you may have target player discard a card.

How it works : Hollowsage

Original English text — Wizards of the Coast / Scryfall

#1May 1, 2008· Wizards of the Coast
If Hollowsage becomes untapped during your untap step, the ability will trigger. However, since no player gets priority during the untap step, it waits to be put on the stack until your upkeep starts. At that time, all your “beginning of upkeep” triggers will also trigger. You can put them and Hollowsage’s trigger on the stack in any order.
No other card is named in this ruling.