Even though I am not clear how to specify a new technology. And if I may be useful in this case.
I'd also like to understand how to specify a squad instead of a single unit under the spell of evocation.
Once evoked the unit, there is the opportunity of changing the equipment ?
You cannot summon anything but a singular unit in E:wom, as far as I know. It is possible in FE.
You cannot upgrade a summoned unit in E:wom, unless it is a champion, in which case you will get the regular level-up points. It is possible to upgrade equipment on units in FE, given the right circumstances.
This is an example of a tech that unlocks your spellbook
<TechDef InternalName="Test_Tech">
<DisplayName>Book of Test</DisplayName>
<Description>This breakthrough allows our Kingdom to use spells from the Book of Test.</Description>
<Image>EarthCrystal_Medallion.png</Image>
<Rarity>100</Rarity>
<Category>Non-existant</Category>
<Infinite>0</Infinite>
<AppearanceChance>100</AppearanceChance>
<AIData AIPersonality="AI_General">
<AIPriority>50</AIPriority>
<AITradeToGetValue>75</AITradeToGetValue>
<AITradeOutValue>90</AITradeOutValue>
<AIAtWarMultiplier>1</AIAtWarMultiplier>
<AIEarlyBuildUpMultiplier>1</AIEarlyBuildUpMultiplier>
</AIData>
<GameModifier>
<ModType>Player</ModType>
<Attribute>UnlockSpellbook</Attribute>
<StrVal>Test_Spellbook</StrVal>
<Value>0</Value>
</GameModifier>
</TechDef>
Now you must find a way to unlock this tech. For this, you use the following modifier
<GameModifier>
<ModType>Player</ModType>
<Attribute>UnlockTech</Attribute>
<StrVal>Test_Tech</StrVal>
</GameModifier>
but where do you place it? That depends where you want to place it. It can be placed inside buildings, for example. It can also be given as faction-bonus for a faction. Here is an example of such a bonus
<AbilityBonus InternalName="Test_SpellBook">
<AbilityBonusOption InternalName="TestSpellbook1">
<DisplayName>Test Spellbook</DisplayName>
<Description>Faction starts with Test Spellbook</Description>
<Bonus>10</Bonus>
<Cost>2</Cost>
<GameModifier>
<ModType>Player</ModType>
<Attribute>UnlockTech</Attribute>
<StrVal>Test_Tech</StrVal>
</GameModifier>
</AbilityBonusOption>
</AbilityBonus>