Without regard for the consequence (anubandha), loss, violence (hiṃsā), and one's own capability (pauruṣa), Action (karma) which is undertaken out of delusion (moha), that is called of darkness (tāmasa).
Action defined by dark inertia is undertaken in delusion, without concern for consequences, for death or violence, or for manhood.
(25) The work embarked on by a man deluded who has no thought of consequence, nor [care at all] for the loss and hurt [he causes others] or for the human part [lie plays himself], is called [a work] of Darkness.
18.25 That action is said to be born of tamas which is undertaken out of delusion, (and) without consideration of its consequence, loss, harm and ability.
18.25 That act is said to be Tamasika which is undertaken through delusion, without regard to consequences, loss, injury and one's own capacity.
18.25 That action which is undertaken from delusion, without a regard for the consequences, loss, injury and (one's own) ability -- that is declared to be Tamasic (dark).