Such triggered abilities start with "when" or "whenever." Some keyword abilities also include a triggered ability that happens when a permanent enters the battlefield
This is an early iteration of this effect, and one that has been surpassed by dozens of other cards over the years
Zhulodok, Void Gorger Arguably the first eldrazi designed to be a commander, Zhulodok, Void Gorger gets extra value from that most favorite of words to see on your expensive spells: Cascade
With Saskia out, your Soldiers become even more efficient, dealing damage across two different players, giving you the potential to take out two players at once
The best examples are in the Ravnican Simic cards, which usually have a theme that benefits from manipulating counters
If you want to spend a little more, youd be best off choosing a win condition to go along with some of the more expensive cards mentioned today