Ms. Bumbleflower triggers, causing an opponent to draw a card who cannot pay for
Smothering Tithe's trigger, and putting a +1/+1 counter on a creature.
Smothering Tithe triggers, creating a Treasure token, as the opponent who drew a card cannot pay for its trigger.
When
Shrieking Drake enters, it triggers, returning it from the battlefield to your hand.
Activate the Treasure by tapping and sacrificing it, adding ({U} magic symbol) .
Repeat.
Notes
You can repeat this combo until the opponent loses the game due to drawing from an empty library. If multiple opponents cannot pay for
Smothering Tithe's trigger, you can perform this loop for each of those opponents. You may start this combo with the opponent being able to pay for Smothering TIthe's trigger so long as you provide enough ({U} magic symbol) to outlast their mana supply.