Eye-ra is a kamikaze unit that explodes, killing itself upon attack. Friendly fire does not apply to Eye-ras, so they won't hurt your own monsters when they explode.
Eye-ra's will attack the nearest wall and will deal splash damage to structures and monsters in the immediate area, pay close attention to the lay-out of the enemy yard and plan accordingly to possibly take out multiple buildings or the enemy champion with fewer Eye-ras. Be careful where to fling your Eye-ras. It will target stray blocks or messages if it is in their range, wasting the Eye-ra. Use Valgos for these blocks.
Eye-ras wouldn't work well on bases with lure blocks (especially black diamond-walled) since it would take two Level 6 Eye-ras to destroy a single black diamond block (level 6 Eye-ras do 24K damage but black diamond blocks have 27K health). Eye-ras can also be a bunker buster.
Eye-ra also used with Valgos:
WARNING:ATTACK YARDS WHERE THE DEFENSIVE TOWERS ARE FAR FROM THE TOWN HALL OR THE RESOURCE HARVESTERS
1. Hatch many Eye-ras and 20 Bolts or Brains, then incubate 10-20 Valgos depending on the yard.
2. Fling the Valgos to crunch blocks. After all blocks are destroyed, fling Eye-ras near the towers. Eye-ras will kill the tower because there are no blocks.
3. After all towers are destroyed, fling the Bolts or Brains to loot Resources.
4. Watch your monsters defeating the enemy's yard :))
Eye-ras can wipe out entire waves of incoming monsters (even airborne monsters when the Airburst ability is unlocked) when put in bunkers, often quickly deciding the battle.
Players tend to "probe" your bunkers to see what's in them and take out possible Eye-ras because of this strategy. To see what is in your bunker the enemy will send one or two weak monsters, when they approach the bunker your Eye-ras will appear and engage, killing the "probes" but also themselves - so they won't be able to defend your yard in the following attack. To prevent said "probing", simply make sure that your Monster Bunker is not on the very edge of your yard. Make sure it is within the range of several of your turrets to prevent the "probes" from reaching your Eye-ras. Mixing your Eye-ras with several other monsters, (especially fast and powerful monsters) in your bunkers can also help.
In order to prevent an enemy from destroying your defences with Eye-ras, you can simply scatter several blocks around your yard. This will cause the incoming Eye-ras to attack those blocks, only knocking themselves out without causing damage to your structures. If you decide to not work with these "baits" you should consider leaving enough space between your wall and the buildings you intend to protect with them.