You can use my scripts (Make sure you modify it to your own way)
https://raw.githubusercontent.com/kaninhot004/rathena/team-craft/npc/utilities/die_event.txt
He mean when you leeching the monster (Ex. There are tons of high orc behind you)
And anybody kill that orcs.
Leecher will get EXP.
This is possible when you had a party and use even share exp. Then modify EXP received from share will boost EXP by cards.
My way is remember 'Day' that players logged in. (gettimestr)
When player login again on next days, you just use OnPCLoginEvent to check and reset those variables.