[Kingly_Krab]

Merry Christmas, this works 100%, if the NPC is at 1 health it will hit for 0, keep that in mind.

I fixed your issue, shouting the target doesn't return the target's name, also, re-defining things is unnecessary the way you did it.

Also, I put in 'int' in order to keep you from hitting for decimals and keep the health from becoming decimals.

sub EVENT_SPELL_EFFECT_CLIENT 
{  
	my $client = $entity_list->GetClientByID($caster_id);
	if($client->GetTarget()->IsNPC()) 
	{	 
		TESTLIFETAP();
	}
}

sub TESTLIFETAP 
{
	my $client = $entity_list->GetClientByID($caster_id);
	if($client->GetTarget()->GetHP() >= 500) 
	{ 
		$client->GetTarget()->SetHP(int($client->GetTarget()->GetHP() - 500));
		$client->Emote("hit " . $client->GetTarget()->GetCleanName() . " for " . int($client->GetTarget()->GetHP() - 500) . " points of non-melee damage.");
	}
	elsif($client->GetTarget()->GetHP() < 500) 
	{
		$client->GetTarget()->SetHP(int($client->GetTarget()->GetHP() - ($client->GetTarget()->GetHP() * .25)));
		$client->Emote("hit " . $client->GetTarget()->GetCleanName() . " for " . int($client->GetTarget()->GetHP() - ($client->GetTarget()->GetHP() * .25)) . " points of non-melee damage.");
	}
}