Is it helpful if we put together common traps for moncolour? Some for a colour in general, then some for specific colour vs. colour interactions. Something like this:
Red
If Gunpoint Taxman kills a Scavenger belonging to an opponent with no gold, it takes the Scavenger gold.
Reason: combat damage, death, and patrol bonuses are instantaneous events, so the Scavenger gold is gained before Taxman’s ability resolves.
Green
Ferocity only affects units that are in play at the time it’s played.
Moment’s Peace also affects units that arrive after it’s played.
Reason: Ferocity gives something to your units when it’s played: they “get” armour piercing and swift strike. It can’t keep giving something after it’s played. Moment’s Peace states a condition instead, similarly to Free Speech.
Black
If Shadow Blade kills a Technician, the Technician card draw happens before the random discard.
Reason: the damage, and the conditional discard, are two separate effects on the card. This means that instantaneous events, i.e. combat damage, death, and patrol bonuses, happen between the effects.
Purple
Prynn’s midband only activates if she dies from removing a time rune during upkeep, and not if her last time rune is removed in any other way.
Reason: bad card text.
Black vs. Blue/Purple (i.e. factions with indestructible cards that aren’t untargetable)
Disease’s - runes stay on an invulnerable unit when it would die.
Reason: like other runes, - runes are not attachments. If an invulnerable unit would die, it does not lose - runes. If this causes it to have zero health, it’s effectively constantly dying (have fun digitally implementing this), so stays exhausted until it’s brought back to more than zero health.
Purple vs. Blue/Black
If Prynn dies when not at max level, or being affected by Free Speech, any units she banished don’t return to play, but can return later.
Reason: when units are trashed using Prynn’s max-level ability, they are returned to play by Prynn’s other max-level ability. If this ability can’t fire when she dies, they can’t come back. If Prynn comes back into play, then dies when the ability can trigger, they can come back.
Blue vs. Red
If Blue has a Jail in play, Drakk’s max-level ability does nothing.
Reason: Drakk’s max-level ability only triggers when a unit arrives (in play) from hand. Units played from hand go to Jail instead of arriving, and when they’re released they arrive from the Jail, not from hand.