Because of the wording on non-ongoing Schemes, I can use Strionic Resonator to copy their triggers, but I don't know how this works with copying Plots That Span Centuries. If I do copy it, when I set my next Scheme in motion, how many Schemes will be set in motion instead? How does this work with multiple Strionic Resonators? Thanks in advance!
(The link for Plots That Span Centuries is the respective image at magiccards.info.)
In this case, for each time the ability of Plots That Span Centuries resolves, you add two to the number of schemes you set in motion instead the next time you would do so (assuming another scheme wasn't set in motion before all those abilities resolve). Each replacement effect of Plots That Span Centuries applies only to the "next" scheme that you would set in motion, so that even though those effects combine (C.R. 616.2), the operations are additive rather than multiplicative.
(The link for Plots That Span Centuries is the respective image at magiccards.info.)