Cthulhu tentacles

after making a blood pact with Cthulhu by selling 2 souls of sentient creatures 

this summing takes up to three but can have a total of 6 of which four get the pact all that is needed is blood from each participant and to pour one drop of ink in with the blood of the sacrifice and each person will drip this blood onto a candle.  all must be willing participants (the 2 sacrificed participants don't need to know what they're doing or that their sacrifices but must follow the summing) that two of which will be sacrificed the sacrificed souls will be taken by Cthulhu and it will make a pact with you the pact states the following. 

For these souls, I give you an advantage against demons and the demonic speech checks and a spell that makes you summon a tentacle of Cthulhu if you cut your hands and say come forth Cthulhu

how to use the spell you cut your hand taking 1 damage and a tentacle of Cthulhu grows out of the cut and lashes out in front of you doing damage in a cone of 1d6 bludgeoning and 1d6 necrotic damage.