Overabundance — ruling 1

The ability deals one damage even if the land produces no mana when it was tapped to use a mana ability. This can happen with lands that produce a variable amount of mana.

Overabundance — ruling 2

This card’s ability is a mana ability. There is no chance to respond to it in order to prevent the damage. If you want to prevent the damage, you need to use a prevention spell or ability prior to tapping the land for mana.

Overabundance : règles, fonctionnement et interactions (MTG)

Overabundance 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

Whenever a player taps a land for mana, that player adds one mana of any type that land produced, and this enchantment deals 1 damage to the player.

How it works : Overabundance

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
The ability deals one damage even if the land produces no mana when it was tapped to use a mana ability. This can happen with lands that produce a variable amount of mana.
No other card is named in this ruling.
#2October 4, 2004· Wizards of the Coast
This card’s ability is a mana ability. There is no chance to respond to it in order to prevent the damage. If you want to prevent the damage, you need to use a prevention spell or ability prior to tapping the land for mana.
No other card is named in this ruling.