Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Tegan confronts over the Great Crystal
S20E6
·
Snakedance Part 2
To
Crystal resonates with Mara's return
S20E6
·
Snakedance Part 2
Why These Connect
The narrative assertion
"Tegan’s demand in the Chamber of the Mara about who removed the Great Crystal triggers the synchronized activation of the secret vault door in the same moment the TARDIS crystal glows—revealing a supernatural link between her will and the artifact."
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot--remove one and the story structure collapses.