Think of them like minions, except you cast them onto the enemy side. They can be like Altars, mystical stones, ect, little monuments of power.
Totems function like this; during the enemy turn, once their space is passed over, they gain a charge. Like a time bomb before it "detonates" with a spell. Say.. a Fire Totem that casts Meteor Strike in three/four turns. Or a Death Totem that places feints on all enemies/ the closest two to it.
These Totems require an open space to be able to be used, and unlike Minions, they're mostly passive. Ones with a "timer" until "detonation" of a spell would have pips generate backwards to indicate how many turns are left before they activate. This also means that if a totem is spawned, it effectively takes up that space so no extra player/enemy can use that space.
So, they passively take up space, fire off spells every few turns, and have devastating effects. What's the possible downside to them?
AoE spells. Say you're a Ice wizard that casts Blizzard, so it hits all enemies. However, there's a Totem left by another wizard. That totem *will* take damage and most likely be destroyed. Unless the totem functions off of being destroyed, that's it for the totem. Enemy team uses a totem on you? They can't use an AoE spell if they want that totem to stay alive.
They also take traps, shields, and heals that affect all on the same side of the field, like if an enemy uses a Legion shield, the totem would also take the shield even though it's not on their side, aside from being literally on their side of the field.
I think Totems could potentially be a boon for strategy and give a choice to using AoEs to make fights more interesting.