Healing buys more decisions
Healing is strongest when the run is still winnable but mistakes have made the next rooms dangerous. It does not make the build better, but it gives the build more time to prove itself.
Take healing when your current plan is working and health is the only thing threatening it. If the build itself is weak, a reroll may do more than a heal.
Rerolls should fix a specific slot
Active rerolls are for changing the tools you feel in combat. Passive rerolls are for changing the support layer behind the build.
Before spending on a reroll, name the slot that is failing. If you cannot name it, keep the current build and save the resource for a more obvious decision.
Gambits belong to confident runs
Gambit choices are most exciting when you are already clearing rooms well. That is when a risky modifier can turn a good run into a boss-ready run.
If the run is barely alive, gambits can make the next room feel unfair. Take the safer shrine option until your damage, movement, or defenses give you enough control to gamble.