Creeping Trailblazer — ruling 1

The size of the bonus is determined as Creeping Trailblazer's last ability begins to resolve; it won't change later in the turn if the number of Elementals you control changes.

Creeping Trailblazer — ruling 2

Because Creeping Trailblazer is itself an Elemental, its last ability will usually give it at least +1/+1.

Creeping Trailblazer : règles, fonctionnement et interactions (MTG)

Creeping Trailblazer 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

Other Elementals you control get +1/+0. : This creature gets +1/+1 until end of turn for each Elemental you control.

How it works : Creeping Trailblazer

Original English text — Wizards of the Coast / Scryfall

#1July 12, 2019· Wizards of the Coast
The size of the bonus is determined as Creeping Trailblazer's last ability begins to resolve; it won't change later in the turn if the number of Elementals you control changes.
No other card is named in this ruling.
#2July 12, 2019· Wizards of the Coast
Because Creeping Trailblazer is itself an Elemental, its last ability will usually give it at least +1/+1.
No other card is named in this ruling.