Here is the full list of all 30 Seraph achievements.
Unlock a weapon, Ward or Miracle through Transmutation
Destroy a Fountain of Terminus.
Unlock Daemonsight through Transmutation
Attach a Shard to an Oath.
Kill 88 Daemons.
Slay a Lieutenant of Terminus.
Kill an 'enhanced' Elite (Bloody, Tainted, Dark).
Kill the Herald.
Score among the top 75% on a Daily challenge.
Collect 25 story logs.
Equip a Miracle other than Orb or Repel.
Post a score in Survival mode
Kill 50 enemies under the influence of the Double Damage Orb
Transmute the MKII version of each weapon.
Defeat the final threat to Seraph.
Kill the Herald at difficulty 6.0 and above.
Score among the top 25% on a Daily challenge.
Collect 50 story logs.
Collect 75 story logs.
Transmute a MK4 weapon.
Reach 6 pips on the difficulty meter.
Upgrade a Blessing to rank 5.
Reach difficulty 8.0 in Survival or New Game.
Kill 888 Daemons.
Kill 8,888 Daemons.
Reach difficulty 9.0 in Survival or New Game.
Score among the top 10% on a Daily challenge.
Obtain a Supreme Shard.
Defeat the final threat to Seraph at difficulty 8.0 and above.
Seraph is reborn.