He intended for Star and Marco to survive the explosion, but definitely knew it (should have) killed all of Ludo's goons, Ludo included.
Buff Frog got out because Star warned him, Boo Fly could fly away, Ludo just survived because he had a meat and egg shield as a buffer.
Any monster with hate in their heart could have found the wand and the results would have been more or less the same, eventually. Toffee would have guided them as the wand.
But at the same time, Ludo only got back to Mewni from the void because he hit out of nowhere by a burst of green energy, into a dimensional portal back to Mewni that was somehow opened.
Did Toffee somehow cause both of those things to happen? I don't know how he could have, but it's one hell of a coincidence.
Ludo only finds the wand because he hallucinates Star, and chasing after her leads right to the wand.
Was it just a hallucination and another incredible coincidence? Or was it the wand influencing his mind from a distance, or even projecting Star as a magical puppet?
Ludo's mind certainly shouldn't know about Star's new wand, but "Star" has it.
And is it me, or do "her" eyes look awfully green?