Three coloured mana is uncomfortable but easily supportable with cube mana bases, certainly mine
Make sure you have contingency plans in place, such as board wipes or protective spells, to handle nasty surprises and an ever-shifting board
The problem is that our foes can also yield double Counterspells or double "I Don't Like You, Please Stop Doing That" spells
Lastly when your deck needs life gain you are likely a control deck or a very grindy deck
WHAT IN THE HECK IS GOING ON, HERE
Even though you wont find Liliana in any non-Zombie deck, I still could see it having an impact on Standard in the next couple of months before rotation, as many of the same Zombie cards that were in Gerry Thompsons Pro Tour Amonkhet- winning deck are still legal in the format right now