Tikovoth's Possession

You surrender your mind to the fiend, Tikovoth, who takes over your body. Whilst in control, you will have inky black flames envelope a portion of your body, your eyes roll into the back of your head, and from your shoulder, a temporary second head made of black flame appears with crimson eyes. This is Tikovoth, and he is able to communicate with other creatures in this state rather than just being in your head. Whilst Tikovoth is in control, you gain the following bonuses:

• You gain 15 temporary hit points. If any of these remain when the spell ends, they are lost.
• Creatures have disadvantage on DC rolls against spells or cantrips you cast against them.
• You have advantage on to hit rolls on spells or cantrips you cast against enemy creatures.
• When you hit a target with a weapon attack, that target takes an extra 1d6 force damage.
• You can attack twice, instead of once, when you take the Attack action on your turn. You ignore this benefit if you already have a feature, like Extra Attack, that gives you extra attacks.

Tikovoth is unpredictable, with an alignment of Chaotic Evil, and can attack both allies or enemies alike, and so to determine his current status, you must roll a 1d20, with a roll of 10 or above being in favor of your allies, and below meaning they're an active threat to them, and everything else in the immediate vicinity. If the latter happens, the DM is to treat you as an enemy creature and takes control from you as the player until the spell ends, or if you succeed in a DC 20 Wisdom saving throw. Immediately after the spell ends, you must succeed on a DC 15 Constitution saving throw or immediately have your HP lower to 0 as you are rendered unconscious. You remains like this for the rest of the encounter or until someone heals you.

At higher levels: Every few levels, the extra force damage given by a weapon attack increase by 1d6. At 5th level it becomes 2d6, at 11th level it becomes 3d6, at 15th level it becomes 4d6, and at 20th level it becomes 5d6.