All of the books with spells in Doctor Strange have a dangerous commonality: All warnings on risks are after the spells.
Apparently no sorcerers ever sought legal advice. Most warnings are stated before someone takes a medication or engages in a high-risk activity. Consider the rules for drugs and medical devices:
Any drug or device is misbranded unless its labeling bears all of the following information:
(a) Adequate directions for use.
(b) Such adequate warnings against use in pathological conditions or by children where its use may be dangerous to health.
(c) Adequate warning against unsafe dosage or methods or duration of administration or application.
Warnings shall be in a manner and form as are necessary for the protection of users.
Cal. Health & Safety Code § 111375.
Magical warnings placed after spells could result in conditions dangerous to one’s health. The spells do give directions for adequate use, but warnings on possible risks do not appear until after a user starts casting the spell.
Casting spells are not like operating a lawnmower. A person who injured their own foot by running over it with a lawnmower was on notice of multiple warnings in the instruction book and on the lawnmower itself. See, Bell v. Montgomery Ward, 792 F. Supp. 500, 506 (W.D. La. 1992). Moreover, lawnmowers have spinning blades at high speed in order to cut grass. This makes the risk of a lawnmower obvious. A spell is not obvious of any dangerous intent of its normal use within the knowledge of a first-time user.
There is also danger in crossing realms without adequate warning. For example, public beaches require warnings if there are bacteriological dangers that pose a risk to public health. Cal. Health & Safety Code § 115915. There are no warnings on what could be on the other side of a portal opened by a sling ring.
A major theme in the current Doctor Strange comics is magic has a cost. The issue is whether there is adequate warning for what a spell can do. Placing warnings after spells would require the wizard who wrote the book to cast a costly spell to cover damages.