Yeah, statblocks are easy and Templates are less so.
Evocation blocks are basically the same as normal blocks, except it costs 2 shifts to protect a zone with them, they can be used to create armour or a zone border, they end when beaten, and they can be extended by spending shifts when making them or by taking another action to renew them.
Is that what you intend for Magic Eater?
Making Chi Eater weapon 0 would probably help.
You might find it easier to represent that Limitation as a number of different Limitations.