Dragonlair Spider — ruling 1

The triggered ability will resolve and the Insect will be created before the spell that caused it to trigger resolves.

Dragonlair Spider — ruling 2

The triggered ability won’t be affected if the spell that caused it to trigger is countered.

Dragonlair Spider : règles, fonctionnement et interactions (MTG)

Dragonlair Spider 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

Reach Whenever an opponent casts a spell, create a 1/1 green Insect creature token.

How it works : Dragonlair Spider

Original English text — Wizards of the Coast / Scryfall

#1June 1, 2012· Wizards of the Coast
The triggered ability will resolve and the Insect will be created before the spell that caused it to trigger resolves.
Card named in this ruling
Insect
#2June 1, 2012· Wizards of the Coast
The triggered ability won’t be affected if the spell that caused it to trigger is countered.
No other card is named in this ruling.