Extra upkeep effects create additional upkeep steps, allowing abilities that normally trigger once each turn to happen multiple times. This can multiply beneficial upkeep triggers, counters, token creation, and other recurring effects.
Sphinx of the Second Sun creates an entire additional beginning phase, while The Ninth Doctor can add another upkeep when it is untapped. Obeka, Splitter of Seconds goes considerably further by creating extra upkeeps based on the combat damage she deals.
