Quests can be completed by fulfilling a condition described on the card
In regards utility creatures there are a few I have tested, as mentioned World Shaper is a great Splendid reclaimation on stick, I rarely used it for the attack trigger and it normally got a bolt from Omnath, Locus of Rage or sacrificed to one of our many outlets, comboing this with Sylvan Safekeeper , Titania, Protector of Argoth and Omnath, Locus of Rage on the field is explosive
It makes you want to play birds of course, but it also ramps your mana, loads your graveyard, and triggers landfall a whole bunch
Goblin Assassin Goblin Assassin can be an absolute menace in dedicated goblin decks
As long as many of your permanents are mana value 3 or less, you can always have something to return to the battlefield when Sun Titan attacks or ETBs