2015-02-25 : If Dragonlord Silumgar ceases to be under your control before its ability resolves, you won’t gain control of the creature or planeswalker at all.

2015-02-25 : If Dragonlord Silumgar leaves the battlefield, you no longer control it, and its control-change effect ends.

2015-02-25 : If another player gains control of Dragonlord Silumgar, its control-change effect ends. Regaining control of Dragonlord Silumgar won’t cause you to regain control of the creature or planeswalker.