Cards that let you summon 'any number' of units do not resolve properly. #1
Description
Affected Cards
This currently affects 'Body Duplication Mirror' and 'Convening Horn'.
It will also affect 'Counterattack Signal' once that gets implemented.
The Bug
When a card says to summon any number of units, the player should only be allowed to select a set of units that can actually be summoned and will subsequently be forced to pay their costs in a way that does end up summoning those units and won't interrupt processing.
Planned Solution
Currently the plan is to have some form of a CANSUMMON() function that these cards can use as the validator in their SELECT() statements.
Furthermore, the SUMMON() function would then figure out which ways of paying their costs would result in a valid summon and only give the player those options.
Both of these will need to take the special rules for cards like 'Hizama, Magical Flaming Bird', 'Lemur, the Grudge General' or 'Block Wyvern' into account.