Szadek, Lord of Secrets — ruling 1

If another effect would prevent Szadek's combat damage from being dealt to the defending player or replace it with something else, that player chooses which effect applies first. For example, the player can choose to first have Mending Hands prevent 4 of the damage and then apply Szadek's ability so that it gets only one counter.

Szadek, Lord of Secrets : règles, fonctionnement et interactions (MTG)

Szadek, Lord of Secrets 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

Flying If Szadek would deal combat damage to a player, instead put that many +1/+1 counters on Szadek and that player mills that many cards.

How it works : Szadek, Lord of Secrets

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2005· Wizards of the Coast
If another effect would prevent Szadek's combat damage from being dealt to the defending player or replace it with something else, that player chooses which effect applies first. For example, the player can choose to first have Mending Hands prevent 4 of the damage and then apply Szadek's ability so that it gets only one counter.
No other card is named in this ruling.