It is the Wizard's turn, she has moved but hasn't taken an action, she triggers a trap (not an action)
The trap takes effect, the block falls, she takes damage, BP drops to zero, and she relocated to an adjacent square...(*)
But, as it is still her turn (and it has to be for this rule to kick in, as if it is someone else turn then it is too late), and she is a spell caster and has a healing spell and hasn't taken an action on her turn, she can use her action to save herself by casting the healing spell on her turn
All good except at this point (*) the rules state that triggering a falling block (and other traps apart from Spear traps), causes the trap effect; block to fall, damage to be dealt, the hero to be moved AND THEN THIS ENDS THEIR TURN
Perhaps scrapping it is a little hasty on my part, maybe a rewrite...
Modify the existing rule around traps ending your turn, so that they end your movement, but if you have an action remaining then you can use it.
Modify the ‘saving yourself from death text’ (the part relating to spells) to state: If you are reduced to zero BP but have not yet taken your action on your turn, and you are a spell caster with a healing spell then you can use your action to cast it on yourself at once, saving yourself from death. However is this special case the spell will only restore 1 Body point rather than the usual amount.