Underneath the cities of Esper are cycles of life unseen by those who feed them.

Sludge Strider

Whenever another artifact you control enters or leaves the battlefield, you may pay {1}. If you do, target player loses 1 life and you gain 1 life.

Planechase

Whenever another artifact enters the battlefield under your control or another artifact you control leaves the battlefield, you may pay {1}. If you do, target player loses 1 life and you gain 1 life.

Conflux

Whenever another artifact comes into play under your control or another artifact you control leaves play, you may pay {1}. If you do, target player loses 1 life and you gain 1 life.

If Sludge Strider and another artifact enter under your control at the same time, Sludge Strider's triggered ability will trigger. Similarly, if Sludge Strider and another artifact you control leave the battlefield at the same time, Sludge Strider's triggered ability will trigger.

If an artifact creature with 0 toughness enters under your control, Sludge Strider's ability will trigger a total of twice: Once when that creature enters, and once when it's put into a graveyard. Both abilities will be put on the stack after the state-based action check that puts the 0-toughness creature into the graveyard is finished.