Big Slime:

I personally feel like the idea behind summoning slimes is 1. Not original enough as it's just a combo of lich's power and giant slimes power. And 2. It doesn't really fit the idea of a big slime; Why would a big slime be more powerful than a giant slime and for that point why does a big slime even have magic power? Maybe if it was an itermediary between slime and giant slime I'd like it more: Such as if it promoted to giant slime and enhanced the slime life cycle, but even still that wouldn't really feel like a new piece just a useless add-on.

Siphon:

This looks like a viable and interesting piece. I'd have to think about it more as for how to improve it so I probably won't be getting back to you on this one before voting starts.

Skeletal Dragon:

I like the idea of a weaker skeletal dragon existing, but it doesn't really fit theme wise; Why does it gain value from death happening? Why can't it move until a certain number of units have died? Also I'd like to say with how much death needs to happen before it can even move it's a very UP unit. Ex: The last tier requires 9 deaths. With no special summoning units in a game that's more than a quarter of the units in game. Yea you can speed it up by making weak summons and killing them, but I feel pieces should be able to stand on their own to some degree rather than completely relying on the rest of the army or RNG. I also think it'd be better if it somehow connected to the dragon piece or if it had some more skeletal like powers (skeletons for instance can grow from reaching the promotion line or being upgraded by necro and they have longer range than most other minions).

Viking:

Feels like a miniature pride. I don't really get why they give morale to their king tho, doesn't really seem to fit the theme for me.

Time Mage:

Wasn't there a piece called time mage put in the discord channel just yesterday with a very similar ability? Granted this one is different, but still it feels like you grabbed the idea from him and just changed it around a bit. Anyways, can its ability not work if there is unit already in the target's starting square? I feel like this could be useful for setting traps, but also it's a bit OP that it can teleport anywhere its been has the ability to move other units across the board and all of that for such a low cost. With that you could not only stop an enemy's plans you could unravel them entirely which seems a bit OP for a cost of 5, especially when you consider that once it moves around a bit it basically gains global board control.