These are the spoiler tags I use:
Miraculous Ladybug: #ml s5 spoilers / #ml leak / #[episode name] spoilers ((ie, #truth spoilers))
Once Upon Another Time: #ouat spoilers / ((once the new books are released, I will use both this tag and #[book title] spoilers))
The Owl House: #toh spoilers / #[episode name] spoilers ((in the same fashion as above ml spoilers))
The Promised Neverland: #tpn spoilers ((for season 1/the first arc)) / #tpn manga spoilers ((anything not covered by s1)). Probably will no longer be using the first one, as my friend has completed that season.
Young Justice: #yj s4 spoilers
On another note: if you ever need me to tag something (like gore) let me know!
