With 6 Boon slots (5 base + Master at full Boon Collector) and 26 Boons, slot economy matters. Here are the canonical loadouts for the top subclasses.
Artificer
Predation (2), Force of Will (1), Energy Conserver (1), Critical Overdrive (2). Total: 165 Cealts, 6 slots. The Energy Conserver drops Mana Beam cost from 3 to 2; combined with Critical Overdrive's Turn 1 100% Crit, the opener is devastating.
Druid
Cleansing (1), Well Rested (1), Thick Hide (1), Summoner Supreme (1), As One (1), Fortitude (1). Total: 200 Cealts, 6 slots. Druid wants every survivability Boon in the book — the bear handles damage, the Druid handles sustain.
Beast
Jagged Edge (2), Predation (2), Force of Will (1), Wild Ride (2). Total: 175 Cealts, 7 slots — over budget. Drop Wild Ride for Hunter Eyes (1 slot) to fit at 6 slots. Total: 135 Cealts.
Gloom Stalker
Hunter Eyes (1), Critical Overdrive (2), Destined (2), Force of Will (1). Total: 150 Cealts, 6 slots. Destined's random stat allocation is fine for the Gloom Stalker — your burst window doesn't need sustained scaling.
Rampager
Force of Will (1), Force of Will again (different slot variant? No — only one Force of Will). Force of Will (1), Wild Ride (2), Critical Overdrive (2), Thick Hide (1). Total: 170 Cealts, 6 slots.
Bloodkin Warlock
Vampiric Bloodline (2), Force of Will (1), Lunaeia race synergy (free), Predation (2), Weak Points (1). Total: 215 Cealts, 7 slots — over. Drop Predation. Total: 155 Cealts, 5 slots.
General Rule
Force of Will is mandatory for self-damaging builds (Bloodkin, Rampager, Beast with Unleash). Slot it. Don't run more than 6 Boons — the Boon slot cap is 5 base + 1 Master. Save Cealts for the Prestige first.