Underhanded Designs

Whenever an artifact you control enters, you may pay {1}. If you do, each opponent loses 1 life and you gain 1 life.
{1}{B}, Sacrifice this enchantment: Destroy target creature. Activate only if you control two or more artifacts.

Kaladesh Remastered

Whenever an artifact enters the battlefield under your control, you may pay {1}. If you do, each opponent loses 1 life and you gain 1 life.
{1}{B}, Sacrifice Underhanded Designs: Destroy target creature. Activate this ability only if you control two or more artifacts.

Kaladesh

In a Two-Headed Giant game, Underhanded Designs's first ability causes the opposing team to lose a total of 2 life. You still gain only 1 life.

The number of artifacts you control is checked only as you activate Underhanded Designs's last ability. It's not checked again as it resolves.

You can pay {1} only once each time Underhanded Designs's triggered ability resolves. You can't pay more to cause your opponents to lose more life.