Page 189 of V20 (core book) describes the Obtenebration ability "Arms of The Abyss" in this manner:
The player spends a blood point and makes a simple (never extended) Manipulation + Occult roll (difficulty 7); each success enables the creation of a single tentacle. Each tentacle is six feet (two meters) long and possesses Strength and Dexterity ratings equal to the invoking vampire’s Obtenebration Trait — Potence and Celerity dots are added to these Strength and Dexterity ratings, respectively. If the vampire chooses, she may spend a blood point either to increase a single tentacle’s Strength or Dexterity by one or to extend its length by another six feet or two meters. Each tentacle has four health levels, is affected by fire and sunlight as if it were a vampire, and soaks bashing and lethal damage using the vampire’s Stamina + Fortitude. Aggravated damage may not be soaked.
What interests me is this part:
Tentacles may constrict foes, inflicting (Strength +1) lethal damage per turn. Breaking the grasp of a tentacle requires the victim to win a resisted Strength roll against the tentacle (difficulty 6 for each). However, tentacles cannot be used for any kind of manipulation, such as typing or driving.
Do I understand it correctly that tentacles don't have to roll Dexterity to actually hit the foe, just STR to check if the grapple attempt is successfully resisted and then an STR roll for damage?
Or do the tentacles roll their Dexterity to check if they hit the foe first?
Thanks in advance.
UPD: adding some more questions from comments.
Do the tentacles contibute to "Multiple Opponents" then, as listed on page 276?
Multiple Opponents: A character who battles multiple opponents in close combat suffers attack and defense difficulties of +1, cumulative, for each opponent after the first (to a maximum of +4).
Can I parry them with a weapon and inflict damage if the parry is successful?