Beginning of the End

Beginning of the End is the final stage in The Holy Grail War.

Battleground

 * Squire Rel spawns at the start.
 * After 3.3 seconds, 3 Otta-smack-us spawn.
 * Rin Tohsaka spawns as the boss after 13.3 seconds.
 * After 16.7 seconds, another Squire Rel spawns.
 * After 20 seconds, Croco starts spawning infinitely every 16.7~20 seconds.
 * After 26.7 seconds, 5 Duches spawn, delay between them is 33.3~36.7 seconds.
 * After 40 seconds, Celeboodle starts spawning infinitely every 33.3~50 seconds.
 * 2 more Otta-smack-us spawn after 41.7~43.3 seconds.
 * After 46.7 seconds, Squire Rel starts spawning infinitely every 6.7~16.7 seconds.
 * Illyasviel spawns after 50 seconds.
 * The last Otta-smack-u spawns after 81.7~83.3 seconds.

Reference

 * https://battlecats-db.com/stage/s02052.html