Modal cards are often interaction, which lend themselves well to a controlling shell, and you can use Riku as a source of card advantage and a threat to close the game out with
Speaking of Palinchron, its also very easy for a mono-blue deck to find ways to go infinite with its mana, which can translate to infinite blink effects, card draw, tapping down all your opponents creatures with Thassa, and other extremely convenient side benefits that can set you up to win the game
Iconic cards, meanwhile, now take the crown as Lorcanas rarest chase cards
= Check out the coverage of Pro Tour - Venice at Sideboard.com in March to see if these were played in Onslaught Block Constructed
For more information on Wheel of Potentials current issues and different errata options, check out this helpful video
Guess the thoughtseize play is actually a little better