Forum:Malefic Truth Dragon/Field Spell Activation

Alright, so, I know that if you activate a new field spell (such as a Malefic World over a Geartown) while a Malefic monster is out, the Malefic, (like, say Malefic Cyber End Dragon) on the field will be destroyed. My question is, when that malefic is destroyed, could I special summon a Malefic Truth Dragon in reaction? I know that I can get him out, but will the other field spell have taken effect by then so that I wouldn't be simply wasting half of my life points?

Another question, if Malefic Truth is destroyed by battle or card effect, and he's the only one I have in my graveyard/hand, can I special summon him again?

Thanks in advance!