You may do so any number of times for any specific ability, as long as you can pay the cost and choose legal targets each time, and of course, provided that the ability text or the game rules do not state otherwise
Unfortunately, youll have to draw them over the next two turns, so youll be stuck with those two bad cards regardless
Sidisi, Brood Tyrant helped define this wedge in the original Khans of Tarkir and will mill three when it arrives or attacks, and then when one or more creatures are put in your graveyard from your library, you make a free 2/2 Zombie token
Advanced Game Mechanics Ability Lock: Some cards prevent Abilities from being used, limiting an opponents strategy
And everybody loves lords, especially those that make creatures to buff
So if youre playing a commander like Gyruda or Hidetsugu and Kairi, Clever Impersonator should really be in your deck