Blink

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after IV.)
I, III — Choose target creature. Its owner shuffles it into their library, then investigates. (They create a Clue token.)
II, IV — Create a 2/2 black Alien Angel artifact creature token with first strike, vigilance, and "Whenever an opponent casts a creature spell, this permanent isn't a creature until end of turn."

Doctor Who

As the triggered ability of the Alien Angel token resolves, it continues to be an artifact but will stop being both an Alien and an Angel until it becomes a creature again.

If an opponent casts a creature spell with flash while the token is attacking or blocking, the token is removed from combat because it stops being a creature. However, any creatures that it was blocking are still considered blocked.

People often assume that Sagas are a strict progression from top to bottom, but actually, from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly wobbly, timey-wimey . . . stuff. That is, the rules support chapter abilities that appear to be out of order, like those on Blink. The first ability triggers when the first and third lore counters are added. The last ability triggers when the second and fourth lore counters are placed on it.