Survivor of the Unseen does not have summoning sickness.
({4} magic symbol) ({W} magic symbol) available.
Steps
At the beginning of your upkeep, Survivor of the Unseen's cumulative upkeep ability triggers.
In response, tap Survivor the Unseen to activate it, drawing two cards, revealing Approach of the Second Sun as you draw it, triggering God-Eternal Kefnet, and putting Approach of the Second Sun on top of your library.
Resolve God-Eternal Kefnet's trigger, copying Approach of the Second Sun and casting it by paying ({4} magic symbol) ({W} magic symbol) .
Sunbird's Invocation triggers, revealing the top seven cards of your library, casting Approach of the Second Sun without paying its mana cost, then putting the rest of the revealed cards on the bottom of your library.
Resolve Approach of the Second Sun, putting it back into your library seventh from the top and gaining you 7 life.
Resolve the remaining copy of Approach of the Second Sun.