I was considering this when Sentinel Tower was spoiled. My initial thoughts was that it could be an additional pay-off card (apart from Monastery Mentor and Young Pyromancer) for the spells matter archetype, and I tinkered around with possible additions that would improve Sentinel Tower without being dead cards in other archetypes. My considerations were all revolved around free spells such as Gitaxian Probe, Manamorphose, Frantic Search and Time Spiral. I wouldn't want to add any rituals since they mainly slot into storm decks without doing anything in other archetypes. You could also consider cards like Guttersnipe, Firebrand Archer and Thermo-Alchemist, although these seem a bit narrow. I ended up dropping the idea since Sentinel Tower only triggers off instant and sorcery spells - if it triggered off all spells like Storm or just noncreature spells like Prowess, I would want to try it out.
Another thing to consider with both Sentinel Tower and Aetherflux Reservoir is that they incentivice you to hold on to your spells untill they hit the battlefield, meaning that your first four turns may be a bit too uninteractive - but i guess that is part of the Storm style of play and the consequences of this depend on how fast the meta is.
If you end up testing it I am also very interested in hearing about the results!
Reliquary Squire GW
Creature - Human (r)
When reliquary Squire enters the battlefield, you may sacrifice a Forest or Plains. If you do, search your library for a land card, put it onto the battlefield tapped, then shuffle your library.
(2/2)
Follower of Tourach B
Creature - Human (r)
Kicker BB (you may pay an additional BB as you cast this spell)
When Follower of Tourach enters the battlefield, if it was kicked, target player discards two cards at random from his or her hand.
(2/1)
Another thing to consider with both Sentinel Tower and Aetherflux Reservoir is that they incentivice you to hold on to your spells untill they hit the battlefield, meaning that your first four turns may be a bit too uninteractive - but i guess that is part of the Storm style of play and the consequences of this depend on how fast the meta is.
If you end up testing it I am also very interested in hearing about the results!
Creature - Human (r)
When reliquary Squire enters the battlefield, you may sacrifice a Forest or Plains. If you do, search your library for a land card, put it onto the battlefield tapped, then shuffle your library.
(2/2)
Follower of Tourach B
Creature - Human (r)
Kicker BB (you may pay an additional BB as you cast this spell)
When Follower of Tourach enters the battlefield, if it was kicked, target player discards two cards at random from his or her hand.
(2/1)