Whisper demonstrates lethal planning.

Whisper is Level 3, Sneak 3 with Social Camouflage 3, Healer 3, and Performer 1 with Misdirection 1.

Contracted to eliminate an enemy spy at a crowded royal feast, Whisper must kill a man while surrounded by hundreds of witnesses without anyone realizing a murder has occurred. She has acquired a rare poison, and brews it into a subtle and deadly syrup.

This is a Sneak example, not Healer, so we summarize: the GM rolls through it with her, and in the end she succeeds and treats one side of her trusty assassin's teapot with it.

At the feast she prepares steaming, aromatic coffee for the guests, and fills both sides of her assassin's teapot. She makes the rounds, filling several cups before and after her target with the excellent coffee in the safe side of the pot. When she fills his cup, she uses the poisoned side. All she has to do is draw no special attention to herself. Here at the feast he is not expecting trouble, and has allowed himself a few glasses of wine. He does not notice her shifting her grip on the pot as she pours his coffee from the poisoned reservoir.

The GM rules all her skills apply, so she is Level 3 + Sneak 3 + Social Camouflage 3 + Performer 1 + Misdirection 1 = EL11.
The enemy spy is Level 4 + Sneak 2 + Performer 3 + Cat's Eye 2 = EL11; the GM rules all his Role ranks and his Cat's Eye Maneuver apply, but his Performer Maneuvers aren't applicable.

The GM gives him a Tipsy -2 Hindrance, for EL9. Without any reason to be suspicious, the GM rolls his resistance at EL9, and he rolls a respectable but predictable 5.
Whisper is the predator here and rolls a little more aggressively with 3 Extra Effort dice for 14d[0-1], taking some risk but trying hard to manipulate the odds. This pays off with a predictable 7.

He thanks her and sips as he flirts up the baroness across from him for several minutes. By the time he eventually begins coughing and clutching his chest, Whisper is already back in the kitchen, just another forgettable servant washing a teapot.