The climbs: Topa Topa, Chief Peak, and a lot of patience
This race is a vertical race. The Topatopa range is steep and unforgiving, and the big climbs to Topa Topa Bluffs and Chief Peak are where your day gets decided. Hike the steep pitches with purpose, keep your effort honest, and treat the early climbs as something to get through cheaply, not to attack. Burn matches in the first few thousand feet because you feel strong and you will be doing math on the side of a mountain at 3 AM wondering where your legs went.
The footing up high is rugged: loose rock, exposed traverses, and trail that demands you actually pay attention. On the 100 and 100K you will hit some of these climbs more than once, in the dark and again tired, so bank good habits early. Power-hiking that feels almost too easy on the first climb is exactly the gear that gets you to the finish.