Hakkar Blood Siphon Spell

Hello community!

I'm trying to fix hakkar spell "Blood Siphon", and i got stuck halfway on solving the problem. I need some guidance from more experienced developers.
By the description on wowwiki tactics you can read:

[li]Blood Siphon: Every 90 seconds from the time that Hakkar is pulled he will cast Blood Siphon on the entire raid. In its base state this is a 8 second channeled drain that deals 200 damage per second, stuns, and heals Hakkar for 1000 health per second. However, if the player has been infected with Poisonous Blood (released as a cloud around the corpse of a Son of Hakkar) then the Blood Siphon changes its effect. The stun remains but it now does 200 damage per second to Hakkar. Blood Siphon will appear as a debuff for each person affected. The number of these debuffs will remove nearly all existing ones. [/li]
So, i’ve searched for blood siphon spell using the command “.lookup spell blood siphon” and i found two spells/auras that fit on this mechanic: (one is for when you DON’T have the poisonous blood buff and other when you HAVE the poisonous buff, these spells can become auras and get mutiple stacks depending on the situation)

I tested them, and found out that both of them are channelling directly on the caster itself, wich is wrong.
The first step i took was to make it somewhat get a target, so i looked into SpellMgr.cpp under LoadSpellInfoCorrections() and coded the following:

    //Hakkar - Blood siphon
        case 24322: 
        case 24323:
                  spellInfo->Effects[EFFECT_0].TargetA = SpellImplicitTargetInfo(TARGET_UNIT_CASTER);
                  spellInfo->Effects[EFFECT_1].TargetB = SpellImplicitTargetInfo(TARGET_UNIT_TARGET_ENEMY);

This enabled me to target someone with the spell, maybe i could do this with the "conditions" table that i also found out that may be possible to do the same but, when i saw a video of the mechanic itself intrigued me in how this should be done.

I needed the channeling to hit multiple targets instead of just one (depending in how you got poisonous blood or not). (id: 24322) (how to do this?)
If you got poisonous blood, then channelling spell 24323 should be cast on you. (boss could be channelling two different spells at the same time for different targets depending if you got the poisonous blood or not)
Both spells get stacks depending on how many players fit these conditions. (i think this mechanic is already working since i tested with the .aura command)

you can see some of the behavion in here:


How can i achieve this behavior? I’ve scripted bosses and such but never got deeper into this kind of stuff.
Can someone show me a similar mechanic or guide me into the correct functions?

Thank you all.