Kalex, Sister of Athax

As long as you control a plainswalker named
Athax, this creature gets +3/+3 and has
"At the beginning of your end step, return
target Demon creature card from your
graveyard to the battlefield."
"Brother Athax has been blessed to be given a spark,
now he seeks to expand his glorious monopoly to these
other "Planes". I will continue to uphold my duty, and
provide him loyalists."