To clarify and deepen my understanding of the Tower, I pondered the following comparisons with similar and/or opposing cards. Maybe my comparisons will inspire you to make your own!
Authority / Leadership
Tower: A cold, impersonal, impartial leading figure or type of guidance. "Artificial" authority that comes from the position one has, no matter whether one's personality type is suited to the job or not.
Bear: A strong, charismatic, warm-blooded, and personally involved leading figure or type of guidance. Natural authority.
Dog: A person who can (emotionally) support and help but isn't able to guide or lead.
Child: Leadership in the form of gentle guidance and support is needed to gain experience safely. Bear might be too loud or over-protective; Tower too strict and cold - a good dose of Dog would help while Dog only might be too weak.
Clouds: Lack of leadership and guidance - guidance would be needed to get out of confusion or despair. Both Bear and Tower could help a lot here but in the end mightn't help with becoming self-reliant and might thus keep the querent in dependence on their leadership.
Power
Tower: Power through position. Power in the sense of control.
Bear: Power in the sense of natural authority. Powerful, personality. Power in the sense of dominance.
Snake: Hunger for power. Diplomatic or political power.
Independence
Tower: The type of independence arising from a lack of close emotional relationships, or from working or living alone.
Fox: Independence from others' judgements (moral, aesthetic, political etc.) - to stick with what we have found to be true no matter what it costs.
Dog: Dependence - in general, but especially the dependence on the approval and love of others.
Anchor: Dependence in the sense of being stuck with something or someone, of being tied to someone or something by practical necessities.
Ring: Dependence in the sense that we're bound by a promise, or because we can't that easily "undo the ties that bind us".
Open vs. Close, Yes vs. No
Tower: To shut others out, to distance oneself from others or from some experiences. To say "no" to something. To forbid something.
Key: To let others in, to embrace someone or something, to open oneself up to an experience. To say "yes" to something. To allow something.
Exclusion
Tower: To exclude others from one's emotional life and thoughts; to prevent them from coming into one's private sphere.
House: To exclude strangers, non-family members; to not welcome someone into one's family or circle of close friends. To ward off anything that is unfamiliar or different.
Book: To keep others purposefully unaware of or uneducated about something and thus keep them "outside" the esoteric circle. Excluding others in the sense of elitism.
Key: The opposite of exclusion. To open one's door to others - literally and figuratively speaking. To meet others without fear or distrust but with open heart and mind. To welcome strangers. To let others be part of a secret.
Defence , protection
Tower: Protection and/or self-defence by putting up (and asserting) boundaries.
Bear: Protector; protection of others, protective behaviour. To make provisions for the future.
Fox: Self defence. Self-care. To look after oneself first.
