Zendikar Resurgent

Whenever you tap a land for mana, add one mana of any type that land produced. (The types of mana are white, blue, black, red, green, and colorless.)
Whenever you cast a creature spell, draw a card.

The List

Commander 2017

Whenever you tap a land for mana, add one mana to your mana pool of any type that land produced. (The types of mana are white, blue, black, red, green, and colorless.)
Whenever you cast a creature spell, draw a card.

Oath of the Gatewatch

Oath of the Gatewatch Promos

If the land’s mana ability produces more than one type of mana, choose one of those types to determine what mana Zendikar Resurgent produces.

The last ability will resolve before the creature spell that caused it to trigger.