In some unusual cases, you may end up putting the appropriate counters on more than one permanent. For example, if you control The Ozolith when Parish-Blade Trainee dies, you'll put the appropriate number of each kind of counter onto both The Ozolith and the target creature.
Once a creature's training ability has triggered, destroying the other attacking creature or reducing its power won't stop the creature with training from getting a +1/+1 counter.
A creature's training ability triggers only when both that creature and a creature with greater power are declared as attackers. Increasing a creature's power after attackers are declared won't cause a training ability to trigger.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Zara Alfonso
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Parish-Blade Trainee's last ability doesn't cause you to move counters from itself to the target creature. Rather, you put the same number of each kind of counter Parish-Blade Trainee had when it died onto that creature.
Parish-Blade Trainee's last ability puts all of its counters onto the target creature, not just its +1/+1 counters.
If Parish-Blade Trainee has -1/-1 counters on it when it dies, the last ability will include those as well. This may result in the recipient also dying.
