Cosmo, Scroll of Ancestral Tapestry

During your turn, auras you control with ward are weapons with base

equal to their ward and "Once per Turn Action -

: Attack"

Your aura attacks with one or more +1

counters get go again.

Your illusionist auras are considered to be weapons during your turn only, not just during your action phase (as with Iris of Reality or Luminaris) nor all the time (as with Reality Refractor).
Cosmo has a static effect. If you attack with an aura with ward, and then give it one or more +1 counters, that aura’s attacks get go again.
If you attack with an aura, the aura attack only has go again if another effect has given the attack go again from an effect (e.g. Cosmo’s static effect). The aura attack does not have go again just because the aura has go again from when it was played. For example, attacking with Burn them All does not mean its attacks will always have go again just because Burn them All has go again on it.
Attacks with an aura with an aura retain the properties (such as color strip) of that aura.

Older rulings (1)

~~If you give an aura attack go again after it has resolved and you’ve passed the link step for that chain link, you will not retroactively gain an action point from giving go again.~~
Changed 2025-01-31
The Link Step no longer exists (31 January 2025): the action point from go again is given as the Resolution Step begins, right after the Damage Step; read "link step" as "the start of the Resolution Step". Go again gained after that gives nothing.

SubtypesScroll, 2H