We's Bigger:
Lower the cost the next unit you play this turn by 1. This unit comes into play with 1 damage on it.
Defend the Border
While DTB has 3 or more resource tokens on it, redirect the first point of damage done to your capital each turn to another target unit or capital.
Thinking about the rules for simultaneous events (active player decides order to play them) and the word cancel (which, presumable, means the damage/card/etc ceases to exist)
my interpretation of these two cards
We's Bigger: if you play 2 or more of these cards, the unit should come into play with only ONE damage. There is nothing in the card which says "add 1 damage". It simply states, it comes into play with one damage. So if you resolve each card in order.
first we's Bigger: cost for next unit is lowered by one, it will come in with one damage
second We's bigger played: lower the cost by one more (now -2 cost). It will come in with one damage (ONLY ONE DAMAGE).
its probably the designers intention to say "add one damage" but that is simply not how they wrote the card.
By "Read the rules, dummy" interpretation, and not trying to guess the designers intention, 2 We's biggers = 1 damage
Now Defend the border
player one inflicts 1 damage to player 2's capital
player 2 has 2 defend the borders that are fully stacked with tokes to have 2 full effects
1st point of damage is canceled, obviously. player 2 decides to use his DTB #1 to cancel the first damage (simultaneous actions, active player decides order)
at this point, that "first point of damage" has been canceled, and is NO LONGER DAMAGE. The 2nd DTB is not triggered
this is similar to damage that is inflicted by a unit with sadistic mutation. If a unit with SM does one damage in combat, and that damage is canceled, SM DOES NOT trigger, because NO DAMAGE WAS INFLICTED. DTB doesnt say first damage ASSIGNED. It says first damage DONE to the canel, implying APPLIED DAMAGE
why is this important? well
now player 1 inflicts 1 more damage to player 2's capital
player 2 NOW CAN USE THE 2nd DTB to cancel what is now "the first point of damage to the capital".
That is different from prior interpretations.
I believe that by the EXACT wording of the 2 cards and rules of canceling, constant effects, and simultaneous actions
2 We's biggers result in only 1 damage to the summoned unit
and 2 Defend the borders can redirect the first 2 points of damage to its capital.
I make no judgements about the designers' intentions. but this is the exact wording of the rules.