People still lure it to the corner sometimes
That is a waste of time and troops. Flush it out and then do the two poisons to get rid of it. But I don't do that with a hound; save those poisons for the pups and sskelly traps.
Stacking Lev 4 and Lev 2 works
I do it all the time in war with my TH 9 account. I place the lev 4 first and stack it immediately with the lev 2. Dead max drag every time. If I place the lev 2 first, the drag sometimes survives with a sliver of hp (and then dies against a minion or lava pup) but still, why take the chance. Drop the lev 4 first.