In an ideal situation, you would use Lethal Scheme to kill a huge threat, but sometimes the cards are more important
Offering bounce and once-per-combat locked card draw, Miguel OHara is expensive for minimal upside
And Grave Titan merely makes Zombies, rather than being one
Hostage Taker may be somewhat under the radar, since its a blue and black creature, but when you remember that last set we had The Scarab God, and now theres Hostage Taker, playing a U/B creature deck starts to look more and more intriguing
The Extended decks that Watchwolf would naturally go in have creatures that are just that little bit more outrageous, and the last few years have raised the bar to the point where Watchwolf no longer stands out
However, now that Vein Ripper has basically disappeared following the ban of Sorin, Imperious Bloodlord, Pioneer has become hospitable for Cauldron Familiar strategies again