I'd like to name this cycle after a cycle of rare legends, something like "Lesthan's Call" and suchlike. Wizards haven't done one of those cycles since they've been printing planeswalkers, though, because they'd rather their planeswalkers become the iconic characters things are named after (as in the Ajani's Mantra cycle and the Ajani's Pridemate cycle). I do have five planeswalkers planned for the block, but only two in this first set - the other three are later in the block, so that's not a great option.

So I might just name this cycle after legends anyway, and let the planeswalkers have their own associated cards later. I've already got legends in black, blue and green; just need red and white, and several of the white rare creatures could be easily made into a legend.