You choose whether to sacrifice an artifact or not as Ironclad Revolutionary’s ability resolves. No player may take actions between the time you choose whether to sacrifice an artifact and, if you do so, the time that counters are added and life is lost.

You can sacrifice an artifact only once when Ironclad Revolutionary’s triggered ability resolves. You can’t sacrifice more to get more counters or more life loss.

In a Two-Headed Giant game, Ironclad Revolutionary’s ability causes the opposing team to lose a total of 4 life.