Lich does not double up Niv-Mizzet, Ghost Counsel's draw engine. It replaces the life gain with card draw before the gain happens, so Niv never gets a lifegain trigger from that event.
Setup / catch: Lich must be on the battlefield when you would gain life. Lich replaces the life gain with drawing that many cards, so no life is gained and Niv's 'whenever you gain life' ability does not trigger from that event.
What to check next: Remember that Lich replaces the life gain rather than causing a second event. Niv can trigger only from a life-gain event that actually happens. Also account for Lich's severe drawback if it is put into a graveyard from the battlefield.
Loot can hit hard in combat while his power is deeply negative, but Altar of Dementia does not get the same conversion. Sacrifice a negative-power Loot to the Altar and it reads his actual last-known power, so the mill result becomes zero instead of turning a large negative number into a large mill.
Setup / catch: Loot's power is negative when he is sacrificed to Altar of Dementia. His positive-power treatment applies only to assigning combat damage.
What to check next: Before using a sacrifice payoff that references Loot's power, check whether it is combat damage or a different effect. Loot's special positive treatment applies only to assigning combat damage; noncombat effects use his real power.
