Time Spiral block is a block that focuses on aspects of time. Each set has mechanics that tie into this, but the block is set up in a way that Time Spiral is about the past, Planar Chaos is about the present and Future Sight is about the future. The past is referenced in Time Spiral in two ways. First there is a separate set included (with purple expansion symbols) that consists of cards from the past. These are the timeshifted cards. Secondly all cards in the set reference older cards in one or more ways.
In addition to the 301 normal cards are 121 additional cards (one in each booster). These cards are not actually part of the set but do coexist with the cards from the Time Spiral set.
To tie in with the theme of past cards, older mechanics were re-used in this set to give it more of a nostalgic feel. The team working on Time Spiral decided to bring back the following mechanics: buyback, echo, flanking, flashback, madness, morph, shadow, spellshaper, storm, thallid and last but not least slivers.
On top of that there were a few new abilities. First of these is suspend. Suspend is tied to the theme of time very directly. The spell is removed from the game for a few turns and after a while is played as normally. The caster of the spell is actually using time as a resource for playing it.