What are the names of the opponents and other features of the Trials

My experience, paired with documentation gives this simple explanation.

• Growth: Cheap(ish) units that have a lot of effects or have spells that help them grow or summon other units.
• Energy: These scrolls hit hard and are intended to do a lot of damage, quickly.
• Order: Order scrolls tend to be rather weak as single-units but can gain strength when other order units are played in close proximity to them. Many of these units give a lot of bonuses to their fellow units when they are near by.

In my opinion, the Order type requires the most game-play strategy while the other two types can do well from a basic deck-level strategy and a bit of luck. It's been argued that this makes the game rather unbalanced, against Order.

Your turn consists of the following events:

1. For each of your units: “beginning of turn” effects such as poison or healing (e.g. Elan Vital, Ranger's Bane, Searing Shackles) are applied.

2. For each of your units: its Countdown is decreased by 1, possibly triggering “Countdown becomes 0” effects (e.g. Vitality Well, Honorable General).

3. You receive one scroll, and your current resources are restored to maximum levels.

4. You are given control until you push the end-turn button or the timer expires. During this phase you can:

   • Use scrolls to summon units, cast spells, or enchant creatures. Spell effects and “when [this unit] comes into play” effects occur immediately.

   • Move units to adjacent spaces, up to the limit of their Move stat per turn. Move is not displayed, and is always 1 unless modified (e.g. New Orders, Binding Root, Dryadic Power); the only way to determine current Move is to click on a unit and see if it displays movement arrows for adjacent empty tiles.

   • Sacrifice at most one scroll per turn in exchange for one unit of permanent resource increase (immediately usable) or two scrolls.

   • Use some units' optional push-button actions “when Countdown is 0” (e.g. Tool Initiate, Brother of the Wolf, Machine Priest).

5. Your units will attack (see further steps) only if their Countdown is 0 now; after this point, decreases in countdown caused by events (e.g. Harvester reacting to deaths) will not cause those units to attack.

6. For each of your units which is attacking this turn: “before attacking” effects are triggered (e.g. Ember Bonds, Blightbearer).

7. For each of your units which is attacking this turn: it attacks. (Units attack in order from front to back ranks, and within each rank top to bottom, as if the board were 3 × 5 squares rather than hexagons.) [Need research for “after attacking” effects.]

8. For each of your units whose Countdown is 0: its Countdown is reset to its base Countdown (what is written on its scroll, unless otherwise specified). (As far as I know, there are no effects which trigger on this.)

9. For each of your units: “end of turn” effects (e.g. Searing Shackles, Eager Scryer) are applied.

Glowing tiles mark your units when they have 0 Countdown (will attack at the end of your turn) and your opponent's units when they have 1 Countdown (will attack at the end of their turn).

[I haven't found any documentation of this; my only source so far is my experience from playing. Also, my examples are largely Growth scrolls because I've played them more. Feel free to improve.]

Points of interest:

• The effect of the Countdown rules is that a unit with a Countdown of N written on its scroll attacks every Nth round, counting only turns starting after it enters play (unless it has Haste, in which case it attacks in the same turn it enters play, and with the same timing otherwise).

• If it is your turn and you see your unit and an enemy unit showing the same Countdown — for example, 1 — then the enemy unit will get to attack first, because the order of relevant events is: yours does not attack, they decrement to 0, theirs attacks, you decrement to 0, yours attacks.

• A poisoned unit with 1 Countdown and 1 Health will die before any “countdown becomes 0” effect occurs. (Unknown: What would the combination of Elan Vital and poison do?)

• The positioning of Charge Coil, Ether Pump, or Hellspitter Mortar matters even though it does not control where they attack, because it controls the order of attacking, which can affect how much damage is dealt and how much is wasted on overkill.