Most auramancers would have let the spikes hover just above the skin. Having the spikes rip through the skin from beneath was a touch added by Rakdos himself.
Trample When Riparian Tiger enters the battlefield, you get {E}{E}. Whenever Riparian Tiger attacks, you may pay {E}{E}. If you do, it gets +2/+2 until end of turn.
Whenever Riptide Entrancer deals combat damage to a player, you may sacrifice it. If you do, gain control of target creature that player controls. Morph {U}{U}
As Riptide Replicator enters the battlefield, choose a color and a creature type. Riptide Replicator enters the battlefield with X charge counters on it. {4}, {T}: Create an X/X creature token of the chosen color and type, where X is the number of charge counters on Riptide Replicator.
{2}{U}{U}, Sacrifice Riptide Shapeshifter: Choose a creature type. Reveal cards from the top of your library until you reveal a creature card of that type. Put that card onto the battlefield and shuffle the rest into your library.