Roar of the Crowd — ruling 1

Note that this spell counts the number of permanents you control of the chosen type, not just the number of creatures you control. It will also take your kindred permanents of the chosen type into account.

Roar of the Crowd — ruling 2

You choose a target for this spell as you cast it, but you don't choose a creature type until the spell resolves.

Roar of the Crowd — ruling 3

Spells and abilities that prevent damage or regenerate the targeted creature must be cast or activated before the creature type is chosen.

Roar of the Crowd : règles, fonctionnement et interactions (MTG)

Roar of the Crowd 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

Choose a creature type. Roar of the Crowd deals damage to any target equal to the number of permanents you control of the chosen type.

How it works : Roar of the Crowd

Original English text — Wizards of the Coast / Scryfall

#1April 1, 2008· Wizards of the Coast
Note that this spell counts the number of permanents you control of the chosen type, not just the number of creatures you control. It will also take your kindred permanents of the chosen type into account.
No other card is named in this ruling.
#2April 1, 2008· Wizards of the Coast
You choose a target for this spell as you cast it, but you don't choose a creature type until the spell resolves.
No other card is named in this ruling.
#3April 1, 2008· Wizards of the Coast
Spells and abilities that prevent damage or regenerate the targeted creature must be cast or activated before the creature type is chosen.
No other card is named in this ruling.