Answer:
Union=Marriage
In the range of its impact= Edge of doom
Subject to the whims of change: Bending Sickle's compass
Infinity= Time's fool
Step-by-step explanation:
1) Union is the bringing together of two or more people or things
2) We could always be on the cusp of the end of the world and not know it
3) Compasses are subject to change depending on what direction you're going
4) Infinity is part of the very concept of time. All time comes to an end, but Infinity is the idea that time doesn't stop.