Reverberating Thoughtides

Change the text of each creature you control by replacing all instances of "When X enters the battlefield" with "At the beginning of your end step", where X is that creature's name. (This effect lasts for as long as you control Reverberating Thoughtides.)
Only at the edge of sanity itself, where every thought ebbs and flows like a maddening drumbeat crashing at the edges of the mind, can true knowledge be grasped.